leetcode
  • Introduction
  • Topic summary
    • Backtracking
    • Dynamic programming
    • Binary search
    • Tree
    • DFS BFS
    • Union-Find & 2D matrix
    • Graph
    • Sliding Window
    • Sorting
    • Advanced algorithm
    • Data Structure
    • Bit Manipulation
    • Edge cases - input validation
    • String
    • Array
    • Stack
    • Heap
    • LinkedList
    • Greedy
    • design
    • Trie
  • System Design
    • Jargons
    • Top K problem(heavy hitters)
    • Design Instagram
    • Design Job Scheduler(Async task)
    • Database and file system
      • MySQL relational database
      • Bigtable
      • DynamoDB
      • Cassandra
      • Kafka
      • Chubby
  • Solutions
    • 0001. Two Sum
    • 0002. Add Two Numbers
    • 0003. Longest Substring Without Repeating Characters
    • 0004. Median of Two Sorted Arrays
    • 0005. Longest Palindromic Substring
    • 0006. ZigZag Conversion
    • 0007. Reverse Integer
    • 0008. String to Integer (solutions/atoi)
    • 0009. Palindrome Number
    • 0010. Regular Expression Matching
    • 0011. Container With Most Water
    • 0012. Integer to Roman
    • 0013. Roman to Integer
    • 0014. Longest Common Prefix
    • 0015. 3Sum
    • 0016. 3Sum Closest
    • 0017. Letter Combinations of a Phone Number
    • 0018. 4Sum
    • 0019. Remove Nth Node From End of List
    • 0020. Valid Parentheses
    • 0021. Merge Two Sorted Lists
    • 0022. Generate Parentheses
    • 0023. Merge k Sorted Lists
    • 0024. Swap Nodes in Pairs
    • 0025. Reverse Nodes in k-Group
    • 0026. Remove Duplicates from Sorted Array
    • 0027. Remove Element
    • 0028. Implement strStr(solutions/)
    • 0029. Divide Two Integers
    • 0030. Substring with Concatenation of All Words
    • 0031. Next Permutation
    • 0032. Longest Valid Parentheses
    • 0033. Search in Rotated Sorted Array
    • 0034. Find First and Last Position of Element in Sorted Array
    • 0035. Search Insert Position
    • 0036. Valid Sudoku
    • 0037. Sudoku Solver
    • 0038. Count and Say
    • 0039. Combination Sum
    • 0040. Combination Sum II
    • 0041. First Missing Positive
    • 0042. Trapping Rain Water
    • 0043. Multiply Strings
    • 0044. Wildcard Matching
    • 0045. Jump Game II
    • 0046. Permutations
    • 0047. Permutations II
    • 0048. Rotate Image
    • 0049. Group Anagrams
    • 0050. Pow(solutions/x, n)
    • 0051. N-Queens
    • 0052. N-Queens II
    • 0053. Maximum Subarray
    • 0054. Spiral Matrix
    • 0055. Jump Game
    • 0056. Merge Intervals
    • 0057. Insert Interval
    • 0058. Length of Last Word
    • 0059. Spiral Matrix II
    • 0060. Permutation Sequence
    • 0061. Rotate List
    • 0062. Unique Paths
    • 0063. Unique Paths II
    • 0064. Minimum Path Sum
    • 0065. Valid Number
    • 0066. Plus One
    • 0067. Add Binary
    • 0068. Text Justification
    • 0069. Sqrt(solutions/x)
    • 0070. Climbing Stairs
    • 0071. Simplify Path
    • 0072. Edit Distance
    • 0073. Set Matrix Zeroes
    • 0074. Search a 2D Matrix
    • 0075. Sort Colors
    • 0076. Minimum Window Substring
    • 0077. Combinations
    • 0078. Subsets
    • 0079. Word Search
    • 0080. Remove Duplicates from Sorted Array II
    • 0081. Search in Rotated Sorted Array II
    • 0082. Remove Duplicates from Sorted List II
    • 0083. Remove Duplicates from Sorted List
    • 0084. Largest Rectangle in Histogram
    • 0085. Maximal Rectangle
    • 0086. Partition List
    • 0087. Scramble String
    • 0088. Merge Sorted Array
    • 0089. Gray Code
    • 0090. Subsets II
    • 0091. Decode Ways
    • 0092. Reverse Linked List II
    • 0093. Restore IP Addresses
    • 0094. Binary Tree Inorder Traversal
    • 0095. Unique Binary Search Trees II
    • 0096. Unique Binary Search Trees
    • 0097. Interleaving String
    • 0098. Validate Binary Search Tree
    • 0099. Recover Binary Search Tree
    • 0100. Same Tree
    • 0101. Symmetric Tree
    • 0102. Binary Tree Level Order Traversal
    • 0103. Binary Tree Zigzag Level Order Traversal
    • 0104. Maximum Depth of Binary Tree
    • 0105. Construct Binary Tree from Preorder and Inorder Traversal
    • 0106. Construct Binary Tree from Inorder and Postorder Traversal
    • 0107. Binary Tree Level Order Traversal II
    • 0108. Convert Sorted Array to Binary Search Tree
    • 0109. Convert Sorted List to Binary Search Tree
    • 0110. Balanced Binary Tree
    • 0111. Minimum Depth of Binary Tree
    • 0112. Path Sum
    • 0113. Path Sum II
    • 0114. Flatten Binary Tree to Linked List
    • 0115. Distinct Subsequences
    • 0116. Populating Next Right Pointers in Each Node
    • 0117. Populating Next Right Pointers in Each Node II
    • 0118. Pascal's Triangle
    • 0119. Pascal's Triangle II
    • 0120. Triangle
    • 0121. Best Time to Buy and Sell Stock
    • 0122. Best Time to Buy and Sell Stock II
    • 0123. Best Time to Buy and Sell Stock III
    • 0124. Binary Tree Maximum Path Sum
    • 0125. Valid Palindrome
    • 0126. Word Ladder II
    • 0127. Word Ladder
    • 0128. Longest Consecutive Sequence
    • 0129. Sum Root to Leaf Numbers
    • 0130. Surrounded Regions
    • 0131. Palindrome Partitioning
    • 0132. Palindrome Partitioning II
    • 0133. Clone Graph
    • 0134. Gas Station
    • 0135. Candy
    • 0136. Single Number
    • 0137. Single Number II
    • 0138. Copy List with Random Pointer
    • 0139. Word Break
    • 0140. Word Break II
    • 0141. Linked List Cycle
    • 0142. Linked List Cycle II
    • 0143. Reorder List
    • 0144. Binary Tree Preorder Traversal
    • 0145. Binary Tree Postorder Traversal
    • 0146. LRU Cache
    • 0147. Insertion Sort List
    • 0148. Sort List
    • 0149. Max Points on a Line
    • 0150. Evaluate Reverse Polish Notation
    • 0151. Reverse Words in a String
    • 0152. Maximum Product Subarray
    • 0153. Find Minimum in Rotated Sorted Array
    • 0154. Find Minimum in Rotated Sorted Array II
    • 0155. Min Stack
    • 0156. Binary Tree Upside Down
    • 0157. Read N Characters Given Read4
    • 0158. Read N Characters Given Read4 II - Call multiple times
    • 0159. Longest Substring with At Most Two Distinct Characters
    • 0160. Intersection of Two Linked Lists
    • 0161. One Edit Distance
    • 0162. Find Peak Element
    • 0163. Missing Ranges
    • 0164. Maximum Gap
    • 0165. Compare Version Numbers
    • 0166. Fraction to Recurring Decimal
    • 0167. Two Sum II - Input array is sorted
    • 0168. Excel Sheet Column Title
    • 0169. Majority Element
    • 0170. Two Sum III - Data structure design
    • 0171. Excel Sheet Column Number
    • 0172. Factorial Trailing Zeroes
    • 0173. Binary Search Tree Iterator
    • 0174. Dungeon Game
    • 0175. Combine Two Tables
    • 0176. Second Highest Salary
    • 0177. Nth Highest Salary
    • 0178. Rank Scores
    • 0179. Largest Number
    • 0180. Consecutive Numbers
    • 0181. Employees Earning More Than Their Managers
    • 0182. Duplicate Emails
    • 0183. Customers Who Never Order
    • 0184. Department Highest Salary
    • 0185. Department Top Three Salaries
    • 0186. Reverse Words in a String II
    • 0187. Repeated DNA Sequences
    • 0188. Best Time to Buy and Sell Stock IV
    • 0189. Rotate Array
    • 0190. Reverse Bits
    • 0191. Number of 1 Bits
    • 0192. Word Frequency
    • 0193. Valid Phone Numbers
    • 0194. Transpose File
    • 0195. Tenth Line
    • 0196. Delete Duplicate Emails
    • 0197. Rising Temperature
    • 0198. House Robber
    • 0199. Binary Tree Right Side View
    • 0200. Number of Islands
    • 0201. Bitwise AND of Numbers Range
    • 0202. Happy Number
    • 0203. Remove Linked List Elements
    • 0204. Count Primes
    • 0205. Isomorphic Strings
    • 0206. Reverse Linked List
    • 0207. Course Schedule
    • 0208. Implement Trie (solutions/Prefix Tree)
    • 0209. Minimum Size Subarray Sum
    • 0210. Course Schedule II
    • 0211. Design Add and Search Words Data Structure
    • 0212. Word Search II
    • 0213. House Robber II
    • 0214. Shortest Palindrome
    • 0215. Kth Largest Element in an Array
    • 0216. Combination Sum III
    • 0217. Contains Duplicate
    • 0218. The Skyline Problem
    • 0219. Contains Duplicate II
    • 0220. Contains Duplicate III
    • 0221. Maximal Square
    • 0222. Count Complete Tree Nodes
    • 0223. Rectangle Area
    • 0224. Basic Calculator
    • 0225. Implement Stack using Queues
    • 0226. Invert Binary Tree
    • 0227. Basic Calculator II
    • 0228. Summary Ranges
    • 0229. Majority Element II
    • 0230. Kth Smallest Element in a BST
    • 0231. Power of Two
    • 0232. Implement Queue using Stacks
    • 0233. Number of Digit One
    • 0234. Palindrome Linked List
    • 0235. Lowest Common Ancestor of a Binary Search Tree
    • 0236. Lowest Common Ancestor of a Binary Tree
    • 0237. Delete Node in a Linked List
    • 0238. Product of Array Except Self
    • 0239. Sliding Window Maximum
    • 0240. Search a 2D Matrix II
    • 0241. Different Ways to Add Parentheses
    • 0242. Valid Anagram
    • 0243. Shortest Word Distance
    • 0244. Shortest Word Distance II
    • 0245. Shortest Word Distance III
    • 0246. Strobogrammatic Number
    • 0247. Strobogrammatic Number II
    • 0248. Strobogrammatic Number III
    • 0249. Group Shifted Strings
    • 0250. Count Univalue Subtrees
    • 0251. Flatten 2D Vector
    • 0252. Meeting Rooms
    • 0253. Meeting Rooms II
    • 0254. Factor Combinations
    • 0255. Verify Preorder Sequence in Binary Search Tree
    • 0256. Paint House
    • 0257. Binary Tree Paths
    • 0258. Add Digits
    • 0259. 3Sum Smaller
    • 0260. Single Number III
    • 0261. Graph Valid Tree
    • 0262. Trips and Users
    • 0263. Ugly Number
    • 0264. Ugly Number II
    • 0265. Paint House II
    • 0266. Palindrome Permutation
    • 0267. Palindrome Permutation II
    • 0268. Missing Number
    • 0269. Alien Dictionary
    • 0270. Closest Binary Search Tree Value
    • 0271. Encode and Decode Strings
    • 0272. Closest Binary Search Tree Value II
    • 0273. Integer to English Words
    • 0274. H-Index
    • 0275. H-Index II
    • 0276. Paint Fence
    • 0277. Find the Celebrity
    • 0278. First Bad Version
    • 0279. Perfect Squares
    • 0280. Wiggle Sort
    • 0281. Zigzag Iterator
    • 0282. Expression Add Operators
    • 0283. Move Zeroes
    • 0284. Peeking Iterator
    • 0285. Inorder Successor in BST
    • 0286. Walls and Gates
    • 0287. Find the Duplicate Number
    • 0288. Unique Word Abbreviation
    • 0289. Game of Life
    • 0290. Word Pattern
    • 0291. Word Pattern II
    • 0292. Nim Game
    • 0293. Flip Game
    • 0294. Flip Game II
    • 0295. Find Median from Data Stream
    • 0296. Best Meeting Point
    • 0297. Serialize and Deserialize Binary Tree
    • 0298. Binary Tree Longest Consecutive Sequence
    • 0299. Bulls and Cows
    • 0300. Longest Increasing Subsequence
    • 0301. Remove Invalid Parentheses
    • 0302. Smallest Rectangle Enclosing Black Pixels
    • 0303. Range Sum Query - Immutable
    • 0304. Range Sum Query 2D - Immutable
    • 0305. Number of Islands II
    • 0306. Additive Number
    • 0307. Range Sum Query - Mutable
    • 0308. Range Sum Query 2D - Mutable
    • 0309. Best Time to Buy and Sell Stock with Cooldown
    • 0310. Minimum Height Trees
    • 0311. Sparse Matrix Multiplication
    • 0312. Burst Balloons
    • 0313. Super Ugly Number
    • 0314. Binary Tree Vertical Order Traversal
    • 0315. Count of Smaller Numbers After Self
    • 0316. Remove Duplicate Letters
    • 0317. Shortest Distance from All Buildings
    • 0318. Maximum Product of Word Lengths
    • 0319. Bulb Switcher
    • 0320. Generalized Abbreviation
    • 0321. Create Maximum Number
    • 0322. Coin Change
    • 0323. Number of Connected Components in an Undirected Graph
    • 0324. Wiggle Sort II
    • 0325. Maximum Size Subarray Sum Equals k
    • 0326. Power of Three
    • 0327. Count of Range Sum
    • 0328. Odd Even Linked List
    • 0329. Longest Increasing Path in a Matrix
    • 0330. Patching Array
    • 0331. Verify Preorder Serialization of a Binary Tree
    • 0332. Reconstruct Itinerary
    • 0333. Largest BST Subtree
    • 0334. Increasing Triplet Subsequence
    • 0335. Self Crossing
    • 0336. Palindrome Pairs
    • 0337. House Robber III
    • 0338. Counting Bits
    • 0339. Nested List Weight Sum
    • 0340. Longest Substring with At Most K Distinct Characters
    • 0341. Flatten Nested List Iterator
    • 0342. Power of Four
    • 0343. Integer Break
    • 0344. Reverse String
    • 0345. Reverse Vowels of a String
    • 0346. Moving Average from Data Stream
    • 0347. Top K Frequent Elements
    • 0348. Design Tic-Tac-Toe
    • 0349. Intersection of Two Arrays
    • 0350. Intersection of Two Arrays II
    • 0351. Android Unlock Patterns
    • 0352. Data Stream as Disjoint Intervals
    • 0353. Design Snake Game
    • 0354. Russian Doll Envelopes
    • 0355. Design Twitter
    • 0356. Line Reflection
    • 0357. Count Numbers with Unique Digits
    • 0358. Rearrange String k Distance Apart
    • 0359. Logger Rate Limiter
    • 0360. Sort Transformed Array
    • 0361. Bomb Enemy
    • 0362. Design Hit Counter
    • 0363. Max Sum of Rectangle No Larger Than K
    • 0364. Nested List Weight Sum II
    • 0365. Water and Jug Problem
    • 0366. Find Leaves of Binary Tree
    • 0367. Valid Perfect Square
    • 0368. Largest Divisible Subset
    • 0369. Plus One Linked List
    • 0370. Range Addition
    • 0371. Sum of Two Integers
    • 0372. Super Pow
    • 0373. Find K Pairs with Smallest Sums
    • 0374. Guess Number Higher or Lower
    • 0375. Guess Number Higher or Lower II
    • 0376. Wiggle Subsequence
    • 0377. Combination Sum IV
    • 0378. Kth Smallest Element in a Sorted Matrix
    • 0379. Design Phone Directory
    • 0380. Insert Delete GetRandom O(solutions/1)
    • 0381. Insert Delete GetRandom O(solutions/1) - Duplicates allowed
    • 0382. Linked List Random Node
    • 0383. Ransom Note
    • 0384. Shuffle an Array
    • 0385. Mini Parser
    • 0386. Lexicographical Numbers
    • 0387. First Unique Character in a String
    • 0388. Longest Absolute File Path
    • 0389. Find the Difference
    • 0390. Elimination Game
    • 0391. Perfect Rectangle
    • 0392. Is Subsequence
    • 0393. UTF-8 Validation
    • 0394. Decode String
    • 0395. Longest Substring with At Least K Repeating Characters
    • 0396. Rotate Function
    • 0397. Integer Replacement
    • 0398. Random Pick Index
    • 0399. Evaluate Division
    • 0400. Nth Digit
    • 0401. Binary Watch
    • 0402. Remove K Digits
    • 0403. Frog Jump
    • 0404. Sum of Left Leaves
    • 0405. Convert a Number to Hexadecimal
    • 0406. Queue Reconstruction by Height
    • 0407. Trapping Rain Water II
    • 0408. Valid Word Abbreviation
    • 0409. Longest Palindrome
    • 0410. Split Array Largest Sum
    • 0411. Minimum Unique Word Abbreviation
    • 0412. Fizz Buzz
    • 0413. Arithmetic Slices
    • 0414. Third Maximum Number
    • 0415. Add Strings
    • 0416. Partition Equal Subset Sum
    • 0417. Pacific Atlantic Water Flow
    • 0418. Sentence Screen Fitting
    • 0419. Battleships in a Board
    • 0420. Strong Password Checker
    • 0421. Maximum XOR of Two Numbers in an Array
    • 0422. Valid Word Square
    • 0423. Reconstruct Original Digits from English
    • 0424. Longest Repeating Character Replacement
    • 0425. Word Squares
    • 0426. Convert Binary Search Tree to Sorted Doubly Linked List
    • 0427. Construct Quad Tree
    • 0428. Serialize and Deserialize N-ary Tree
    • 0429. N-ary Tree Level Order Traversal
    • 0430. Flatten a Multilevel Doubly Linked List
    • 0431. Encode N-ary Tree to Binary Tree
    • 0432. All O`one Data Structure
    • 0433. Minimum Genetic Mutation
    • 0434. Number of Segments in a String
    • 0435. Non-overlapping Intervals
    • 0436. Find Right Interval
    • 0437. Path Sum III
    • 0438. Find All Anagrams in a String
    • 0439. Ternary Expression Parser
    • 0440. K-th Smallest in Lexicographical Order
    • 0441. Arranging Coins
    • 0442. Find All Duplicates in an Array
    • 0443. String Compression
    • 0444. Sequence Reconstruction
    • 0445. Add Two Numbers II
    • 0446. Arithmetic Slices II - Subsequence
    • 0447. Number of Boomerangs
    • 0448. Find All Numbers Disappeared in an Array
    • 0449. Serialize and Deserialize BST
    • 0450. Delete Node in a BST
    • 0451. Sort Characters By Frequency
    • 0452. Minimum Number of Arrows to Burst Balloons
    • 0453. Minimum Moves to Equal Array Elements
    • 0454. 4Sum II
    • 0455. Assign Cookies
    • 0456. 132 Pattern
    • 0457. Circular Array Loop
    • 0458. Poor Pigs
    • 0459. Repeated Substring Pattern
    • 0460. LFU Cache
    • 0461. Hamming Distance
    • 0462. Minimum Moves to Equal Array Elements II
    • 0463. Island Perimeter
    • 0464. Can I Win
    • 0465. Optimal Account Balancing
    • 0466. Count The Repetitions
    • 0467. Unique Substrings in Wraparound String
    • 0468. Validate IP Address
    • 0469. Convex Polygon
    • 0470. Implement Rand10(solutions/) Using Rand7(solutions/)
    • 0471. Encode String with Shortest Length
    • 0472. Concatenated Words
    • 0473. Matchsticks to Square
    • 0474. Ones and Zeroes
    • 0475. Heaters
    • 0476. Number Complement
    • 0477. Total Hamming Distance
    • 0478. Generate Random Point in a Circle
    • 0479. Largest Palindrome Product
    • 0480. Sliding Window Median
    • 0481. Magical String
    • 0482. License Key Formatting
    • 0483. Smallest Good Base
    • 0484. Find Permutation
    • 0485. Max Consecutive Ones
    • 0486. Predict the Winner
    • 0487. Max Consecutive Ones II
    • 0488. Zuma Game
    • 0489. Robot Room Cleaner
    • 0490. The Maze
    • 0491. Increasing Subsequences
    • 0492. Construct the Rectangle
    • 0493. Reverse Pairs
    • 0494. Target Sum
    • 0495. Teemo Attacking
    • 0496. Next Greater Element I
    • 0497. Random Point in Non-overlapping Rectangles
    • 0498. Diagonal Traverse
    • 0499. The Maze III
    • 0500. Keyboard Row
    • 0501. Find Mode in Binary Search Tree
    • 0502. IPO
    • 0503. Next Greater Element II
    • 0504. Base 7
    • 0505. The Maze II
    • 0506. Relative Ranks
    • 0507. Perfect Number
    • 0508. Most Frequent Subtree Sum
    • 0509. Fibonacci Number
    • 0510. Inorder Successor in BST II
    • 0511. Game Play Analysis I
    • 0512. Game Play Analysis II
    • 0513. Find Bottom Left Tree Value
    • 0514. Freedom Trail
    • 0515. Find Largest Value in Each Tree Row
    • 0516. Longest Palindromic Subsequence
    • 0517. Super Washing Machines
    • 0518. Coin Change 2
    • 0519. Random Flip Matrix
    • 0520. Detect Capital
    • 0521. Longest Uncommon Subsequence I
    • 0522. Longest Uncommon Subsequence II
    • 0523. Continuous Subarray Sum
    • 0524. Longest Word in Dictionary through Deleting
    • 0525. Contiguous Array
    • 0526. Beautiful Arrangement
    • 0527. Word Abbreviation
    • 0528. Random Pick with Weight
    • 0529. Minesweeper
    • 0530. Minimum Absolute Difference in BST
    • 0531. Lonely Pixel I
    • 0532. K-diff Pairs in an Array
    • 0533. Lonely Pixel II
    • 0534. Game Play Analysis III
    • 0535. Encode and Decode TinyURL
    • 0536. Construct Binary Tree from String
    • 0537. Complex Number Multiplication
    • 0538. Convert BST to Greater Tree
    • 0539. Minimum Time Difference
    • 0540. Single Element in a Sorted Array
    • 0541. Reverse String II
    • 0542. 01 Matrix
    • 0543. Diameter of Binary Tree
    • 0544. Output Contest Matches
    • 0545. Boundary of Binary Tree
    • 0546. Remove Boxes
    • 0547. Number of Provinces
    • 0548. Split Array with Equal Sum
    • 0549. Binary Tree Longest Consecutive Sequence II
    • 0550. Game Play Analysis IV
    • 0551. Student Attendance Record I
    • 0552. Student Attendance Record II
    • 0553. Optimal Division
    • 0554. Brick Wall
    • 0555. Split Concatenated Strings
    • 0556. Next Greater Element III
    • 0557. Reverse Words in a String III
    • 0558. Logical OR of Two Binary Grids Represented as Quad-Trees
    • 0559. Maximum Depth of N-ary Tree
    • 0560. Subarray Sum Equals K
    • 0561. Array Partition I
    • 0562. Longest Line of Consecutive One in Matrix
    • 0563. Binary Tree Tilt
    • 0564. Find the Closest Palindrome
    • 0565. Array Nesting
    • 0566. Reshape the Matrix
    • 0567. Permutation in String
    • 0568. Maximum Vacation Days
    • 0569. Median Employee Salary
    • 0570. Managers with at Least 5 Direct Reports
    • 0571. Find Median Given Frequency of Numbers
    • 0572. Subtree of Another Tree
    • 0573. Squirrel Simulation
    • 0574. Winning Candidate
    • 0575. Distribute Candies
    • 0576. Out of Boundary Paths
    • 0577. Employee Bonus
    • 0578. Get Highest Answer Rate Question
    • 0579. Find Cumulative Salary of an Employee
    • 0580. Count Student Number in Departments
    • 0581. Shortest Unsorted Continuous Subarray
    • 0582. Kill Process
    • 0583. Delete Operation for Two Strings
    • 0584. Find Customer Referee
    • 0585. Investments in 2016
    • 0586. Customer Placing the Largest Number of Orders
    • 0587. Erect the Fence
    • 0588. Design In-Memory File System
    • 0589. N-ary Tree Preorder Traversal
    • 0590. N-ary Tree Postorder Traversal
    • 0591. Tag Validator
    • 0592. Fraction Addition and Subtraction
    • 0593. Valid Square
    • 0594. Longest Harmonious Subsequence
    • 0595. Big Countries
    • 0596. Classes More Than 5 Students
    • 0597. Friend Requests I: Overall Acceptance Rate
    • 0598. Range Addition II
    • 0599. Minimum Index Sum of Two Lists
    • 0600. Non-negative Integers without Consecutive Ones
    • 0601. Human Traffic of Stadium
    • 0602. Friend Requests II: Who Has the Most Friends
    • 0603. Consecutive Available Seats
    • 0604. Design Compressed String Iterator
    • 0605. Can Place Flowers
    • 0606. Construct String from Binary Tree
    • 0607. Sales Person
    • 0608. Tree Node
    • 0609. Find Duplicate File in System
    • 0610. Triangle Judgement
    • 0611. Valid Triangle Number
    • 0612. Shortest Distance in a Plane
    • 0613. Shortest Distance in a Line
    • 0614. Second Degree Follower
    • 0615. Average Salary: Departments VS Company
    • 0616. Add Bold Tag in String
    • 0617. Merge Two Binary Trees
    • 0618. Students Report By Geography
    • 0619. Biggest Single Number
    • 0620. Not Boring Movies
    • 0621. Task Scheduler
    • 0622. Design Circular Queue
    • 0623. Add One Row to Tree
    • 0624. Maximum Distance in Arrays
    • 0625. Minimum Factorization
    • 0626. Exchange Seats
    • 0627. Swap Salary
    • 0628. Maximum Product of Three Numbers
    • 0629. K Inverse Pairs Array
    • 0630. Course Schedule III
    • 0631. Design Excel Sum Formula
    • 0632. Smallest Range Covering Elements from K Lists
    • 0633. Sum of Square Numbers
    • 0634. Find the Derangement of An Array
    • 0635. Design Log Storage System
    • 0636. Exclusive Time of Functions
    • 0637. Average of Levels in Binary Tree
    • 0638. Shopping Offers
    • 0639. Decode Ways II
    • 0640. Solve the Equation
    • 0641. Design Circular Deque
    • 0642. Design Search Autocomplete System
    • 0643. Maximum Average Subarray I
    • 0644. Maximum Average Subarray II
    • 0645. Set Mismatch
    • 0646. Maximum Length of Pair Chain
    • 0647. Palindromic Substrings
    • 0648. Replace Words
    • 0649. Dota2 Senate
    • 0650. 2 Keys Keyboard
    • 0651. 4 Keys Keyboard
    • 0652. Find Duplicate Subtrees
    • 0653. Two Sum IV - Input is a BST
    • 0654. Maximum Binary Tree
    • 0655. Print Binary Tree
    • 0656. Coin Path
    • 0657. Robot Return to Origin
    • 0658. Find K Closest Elements
    • 0659. Split Array into Consecutive Subsequences
    • 0660. Remove 9
    • 0661. Image Smoother
    • 0662. Maximum Width of Binary Tree
    • 0663. Equal Tree Partition
    • 0664. Strange Printer
    • 0665. Non-decreasing Array
    • 0666. Path Sum IV
    • 0667. Beautiful Arrangement II
    • 0668. Kth Smallest Number in Multiplication Table
    • 0669. Trim a Binary Search Tree
    • 0670. Maximum Swap
    • 0671. Second Minimum Node In a Binary Tree
    • 0672. Bulb Switcher II
    • 0673. Number of Longest Increasing Subsequence
    • 0674. Longest Continuous Increasing Subsequence
    • 0675. Cut Off Trees for Golf Event
    • 0676. Implement Magic Dictionary
    • 0677. Map Sum Pairs
    • 0678. Valid Parenthesis String
    • 0679. 24 Game
    • 0680. Valid Palindrome II
    • 0681. Next Closest Time
    • 0682. Baseball Game
    • 0683. K Empty Slots
    • 0684. Redundant Connection
    • 0685. Redundant Connection II
    • 0686. Repeated String Match
    • 0687. Longest Univalue Path
    • 0688. Knight Probability in Chessboard
    • 0689. Maximum Sum of 3 Non-Overlapping Subarrays
    • 0690. Employee Importance
    • 0691. Stickers to Spell Word
    • 0692. Top K Frequent Words
    • 0693. Binary Number with Alternating Bits
    • 0694. Number of Distinct Islands
    • 0695. Max Area of Island
    • 0696. Count Binary Substrings
    • 0697. Degree of an Array
    • 0698. Partition to K Equal Sum Subsets
    • 0699. Falling Squares
    • 0700. Search in a Binary Search Tree
    • 0701. Insert into a Binary Search Tree
    • 0702. Search in a Sorted Array of Unknown Size
    • 0703. Kth Largest Element in a Stream
    • 0704. Binary Search
    • 0705. Design HashSet
    • 0706. Design HashMap
    • 0707. Design Linked List
    • 0708. Insert into a Sorted Circular Linked List
    • 0709. To Lower Case
    • 0710. Random Pick with Blacklist
    • 0711. Number of Distinct Islands II
    • 0712. Minimum ASCII Delete Sum for Two Strings
    • 0713. Subarray Product Less Than K
    • 0714. Best Time to Buy and Sell Stock with Transaction Fee
    • 0715. Range Module
    • 0716. Max Stack
    • 0717. 1-bit and 2-bit Characters
    • 0718. Maximum Length of Repeated Subarray
    • 0719. Find K-th Smallest Pair Distance
    • 0720. Longest Word in Dictionary
    • 0721. Accounts Merge
    • 0722. Remove Comments
    • 0723. Candy Crush
    • 0724. Find Pivot Index
    • 0725. Split Linked List in Parts
    • 0726. Number of Atoms
    • 0727. Minimum Window Subsequence
    • 0728. Self Dividing Numbers
    • 0729. My Calendar I
    • 0730. Count Different Palindromic Subsequences
    • 0731. My Calendar II
    • 0732. My Calendar III
    • 0733. Flood Fill
    • 0734. Sentence Similarity
    • 0735. Asteroid Collision
    • 0736. Parse Lisp Expression
    • 0737. Sentence Similarity II
    • 0738. Monotone Increasing Digits
    • 0739. Daily Temperatures
    • 0740. Delete and Earn
    • 0741. Cherry Pickup
    • 0742. Closest Leaf in a Binary Tree
    • 0743. Network Delay Time
    • 0744. Find Smallest Letter Greater Than Target
    • 0745. Prefix and Suffix Search
    • 0746. Min Cost Climbing Stairs
    • 0747. Largest Number At Least Twice of Others
    • 0748. Shortest Completing Word
    • 0749. Contain Virus
    • 0750. Number Of Corner Rectangles
    • 0751. IP to CIDR
    • 0752. Open the Lock
    • 0753. Cracking the Safe
    • 0754. Reach a Number
    • 0755. Pour Water
    • 0756. Pyramid Transition Matrix
    • 0757. Set Intersection Size At Least Two
    • 0758. Bold Words in String
    • 0759. Employee Free Time
    • 0760. Find Anagram Mappings
    • 0761. Special Binary String
    • 0762. Prime Number of Set Bits in Binary Representation
    • 0763. Partition Labels
    • 0764. Largest Plus Sign
    • 0765. Couples Holding Hands
    • 0766. Toeplitz Matrix
    • 0767. Reorganize String
    • 0768. Max Chunks To Make Sorted II
    • 0769. Max Chunks To Make Sorted
    • 0770. Basic Calculator IV
    • 0771. Jewels and Stones
    • 0772. Basic Calculator III
    • 0773. Sliding Puzzle
    • 0774. Minimize Max Distance to Gas Station
    • 0775. Global and Local Inversions
    • 0776. Split BST
    • 0777. Swap Adjacent in LR String
    • 0778. Swim in Rising Water
    • 0779. K-th Symbol in Grammar
    • 0780. Reaching Points
    • 0781. Rabbits in Forest
    • 0782. Transform to Chessboard
    • 0783. Minimum Distance Between BST Nodes
    • 0784. Letter Case Permutation
    • 0785. Is Graph Bipartite?
    • 0786. K-th Smallest Prime Fraction
    • 0787. Cheapest Flights Within K Stops
    • 0788. Rotated Digits
    • 0789. Escape The Ghosts
    • 0790. Domino and Tromino Tiling
    • 0791. Custom Sort String
    • 0792. Number of Matching Subsequences
    • 0793. Preimage Size of Factorial Zeroes Function
    • 0794. Valid Tic-Tac-Toe State
    • 0795. Number of Subarrays with Bounded Maximum
    • 0796. Rotate String
    • 0797. All Paths From Source to Target
    • 0798. Smallest Rotation with Highest Score
    • 0799. Champagne Tower
    • 0800. Similar RGB Color
    • 0801. Minimum Swaps To Make Sequences Increasing
    • 0802. Find Eventual Safe States
    • 0803. Bricks Falling When Hit
    • 0804. Unique Morse Code Words
    • 0805. Split Array With Same Average
    • 0806. Number of Lines To Write String
    • 0807. Max Increase to Keep City Skyline
    • 0808. Soup Servings
    • 0809. Expressive Words
    • 0810. Chalkboard XOR Game
    • 0811. Subdomain Visit Count
    • 0812. Largest Triangle Area
    • 0813. Largest Sum of Averages
    • 0814. Binary Tree Pruning
    • 0815. Bus Routes
    • 0816. Ambiguous Coordinates
    • 0817. Linked List Components
    • 0818. Race Car
    • 0819. Most Common Word
    • 0820. Short Encoding of Words
    • 0821. Shortest Distance to a Character
    • 0822. Card Flipping Game
    • 0823. Binary Trees With Factors
    • 0824. Goat Latin
    • 0825. Friends Of Appropriate Ages
    • 0826. Most Profit Assigning Work
    • 0827. Making A Large Island
    • 0828. Count Unique Characters of All Substrings of a Given String
    • 0829. Consecutive Numbers Sum
    • 0830. Positions of Large Groups
    • 0831. Masking Personal Information
    • 0832. Flipping an Image
    • 0833. Find And Replace in String
    • 0834. Sum of Distances in Tree
    • 0835. Image Overlap
    • 0836. Rectangle Overlap
    • 0837. New 21 Game
    • 0838. Push Dominoes
    • 0839. Similar String Groups
    • 0840. Magic Squares In Grid
    • 0841. Keys and Rooms
    • 0842. Split Array into Fibonacci Sequence
    • 0843. Guess the Word
    • 0844. Backspace String Compare
    • 0845. Longest Mountain in Array
    • 0846. Hand of Straights
    • 0847. Shortest Path Visiting All Nodes
    • 0848. Shifting Letters
    • 0849. Maximize Distance to Closest Person
    • 0850. Rectangle Area II
    • 0851. Loud and Rich
    • 0852. Peak Index in a Mountain Array
    • 0853. Car Fleet
    • 0854. K-Similar Strings
    • 0855. Exam Room
    • 0856. Score of Parentheses
    • 0857. Minimum Cost to Hire K Workers
    • 0858. Mirror Reflection
    • 0859. Buddy Strings
    • 0860. Lemonade Change
    • 0861. Score After Flipping Matrix
    • 0862. Shortest Subarray with Sum at Least K
    • 0863. All Nodes Distance K in Binary Tree
    • 0864. Shortest Path to Get All Keys
    • 0865. Smallest Subtree with all the Deepest Nodes
    • 0866. Prime Palindrome
    • 0867. Transpose Matrix
    • 0868. Binary Gap
    • 0869. Reordered Power of 2
    • 0870. Advantage Shuffle
    • 0871. Minimum Number of Refueling Stops
    • 0872. Leaf-Similar Trees
    • 0873. Length of Longest Fibonacci Subsequence
    • 0874. Walking Robot Simulation
    • 0875. Koko Eating Bananas
    • 0876. Middle of the Linked List
    • 0877. Stone Game
    • 0878. Nth Magical Number
    • 0879. Profitable Schemes
    • 0880. Decoded String at Index
    • 0881. Boats to Save People
    • 0882. Reachable Nodes In Subdivided Graph
    • 0883. Projection Area of 3D Shapes
    • 0884. Uncommon Words from Two Sentences
    • 0885. Spiral Matrix III
    • 0886. Possible Bipartition
    • 0887. Super Egg Drop
    • 0888. Fair Candy Swap
    • 0889. Construct Binary Tree from Preorder and Postorder Traversal
    • 0890. Find and Replace Pattern
    • 0891. Sum of Subsequence Widths
    • 0892. Surface Area of 3D Shapes
    • 0893. Groups of Special-Equivalent Strings
    • 0894. All Possible Full Binary Trees
    • 0895. Maximum Frequency Stack
    • 0896. Monotonic Array
    • 0897. Increasing Order Search Tree
    • 0898. Bitwise ORs of Subarrays
    • 0899. Orderly Queue
    • 0900. RLE Iterator
    • 0901. Online Stock Span
    • 0902. Numbers At Most N Given Digit Set
    • 0903. Valid Permutations for DI Sequence
    • 0904. Fruit Into Baskets
    • 0905. Sort Array By Parity
    • 0906. Super Palindromes
    • 0907. Sum of Subarray Minimums
    • 0908. Smallest Range I
    • 0909. Snakes and Ladders
    • 0910. Smallest Range II
    • 0911. Online Election
    • 0912. Sort an Array
    • 0913. Cat and Mouse
    • 0914. X of a Kind in a Deck of Cards
    • 0915. Partition Array into Disjoint Intervals
    • 0916. Word Subsets
    • 0917. Reverse Only Letters
    • 0918. Maximum Sum Circular Subarray
    • 0919. Complete Binary Tree Inserter
    • 0920. Number of Music Playlists
    • 0921. Minimum Add to Make Parentheses Valid
    • 0922. Sort Array By Parity II
    • 0923. 3Sum With Multiplicity
    • 0924. Minimize Malware Spread
    • 0925. Long Pressed Name
    • 0926. Flip String to Monotone Increasing
    • 0927. Three Equal Parts
    • 0928. Minimize Malware Spread II
    • 0929. Unique Email Addresses
    • 0930. Binary Subarrays With Sum
    • 0931. Minimum Falling Path Sum
    • 0932. Beautiful Array
    • 0933. Number of Recent Calls
    • 0934. Shortest Bridge
    • 0935. Knight Dialer
    • 0936. Stamping The Sequence
    • 0937. Reorder Data in Log Files
    • 0938. Range Sum of BST
    • 0939. Minimum Area Rectangle
    • 0940. Distinct Subsequences II
    • 0941. Valid Mountain Array
    • 0942. DI String Match
    • 0943. Find the Shortest Superstring
    • 0944. Delete Columns to Make Sorted
    • 0945. Minimum Increment to Make Array Unique
    • 0946. Validate Stack Sequences
    • 0947. Most Stones Removed with Same Row or Column
    • 0948. Bag of Tokens
    • 0949. Largest Time for Given Digits
    • 0950. Reveal Cards In Increasing Order
    • 0951. Flip Equivalent Binary Trees
    • 0952. Largest Component Size by Common Factor
    • 0953. Verifying an Alien Dictionary
    • 0954. Array of Doubled Pairs
    • 0955. Delete Columns to Make Sorted II
    • 0956. Tallest Billboard
    • 0957. Prison Cells After N Days
    • 0958. Check Completeness of a Binary Tree
    • 0959. Regions Cut By Slashes
    • 0960. Delete Columns to Make Sorted III
    • 0961. N-Repeated Element in Size 2N Array
    • 0962. Maximum Width Ramp
    • 0963. Minimum Area Rectangle II
    • 0964. Least Operators to Express Number
    • 0965. Univalued Binary Tree
    • 0966. Vowel Spellchecker
    • 0967. Numbers With Same Consecutive Differences
    • 0968. Binary Tree Cameras
    • 0969. Pancake Sorting
    • 0970. Powerful Integers
    • 0971. Flip Binary Tree To Match Preorder Traversal
    • 0972. Equal Rational Numbers
    • 0973. K Closest Points to Origin
    • 0974. Subarray Sums Divisible by K
    • 0975. Odd Even Jump
    • 0976. Largest Perimeter Triangle
    • 0977. Squares of a Sorted Array
    • 0978. Longest Turbulent Subarray
    • 0979. Distribute Coins in Binary Tree
    • 0980. Unique Paths III
    • 0981. Time Based Key-Value Store
    • 0982. Triples with Bitwise AND Equal To Zero
    • 0983. Minimum Cost For Tickets
    • 0984. String Without AAA or BBB
    • 0985. Sum of Even Numbers After Queries
    • 0986. Interval List Intersections
    • 0987. Vertical Order Traversal of a Binary Tree
    • 0988. Smallest String Starting From Leaf
    • 0989. Add to Array-Form of Integer
    • 0990. Satisfiability of Equality Equations
    • 0991. Broken Calculator
    • 0992. Subarrays with K Different Integers
    • 0993. Cousins in Binary Tree
    • 0994. Rotting Oranges
    • 0995. Minimum Number of K Consecutive Bit Flips
    • 0996. Number of Squareful Arrays
    • 0997. Find the Town Judge
    • 0998. Maximum Binary Tree II
    • 0999. Available Captures for Rook
    • 1000. Minimum Cost to Merge Stones
    • 1001. Grid Illumination
    • 1002. Find Common Characters
    • 1003. Check If Word Is Valid After Substitutions
    • 1004. Max Consecutive Ones III
    • 1005. Maximize Sum Of Array After K Negations
    • 1006. Clumsy Factorial
    • 1007. Minimum Domino Rotations For Equal Row
    • 1008. Construct Binary Search Tree from Preorder Traversal
    • 1009. Complement of Base 10 Integer
    • 1010. Pairs of Songs With Total Durations Divisible by 60
    • 1011. Capacity To Ship Packages Within D Days
    • 1012. Numbers With Repeated Digits
    • 1013. Partition Array Into Three Parts With Equal Sum
    • 1014. Best Sightseeing Pair
    • 1015. Smallest Integer Divisible by K
    • 1016. Binary String With Substrings Representing 1 To N
    • 1017. Convert to Base -2
    • 1018. Binary Prefix Divisible By 5
    • 1019. Next Greater Node In Linked List
    • 1020. Number of Enclaves
    • 1021. Remove Outermost Parentheses
    • 1022. Sum of Root To Leaf Binary Numbers
    • 1023. Camelcase Matching
    • 1024. Video Stitching
    • 1025. Divisor Game
    • 1026. Maximum Difference Between Node and Ancestor
    • 1027. Longest Arithmetic Subsequence
    • 1028. Recover a Tree From Preorder Traversal
    • 1029. Two City Scheduling
    • 1030. Matrix Cells in Distance Order
    • 1031. Maximum Sum of Two Non-Overlapping Subarrays
    • 1032. Stream of Characters
    • 1033. Moving Stones Until Consecutive
    • 1034. Coloring A Border
    • 1035. Uncrossed Lines
    • 1036. Escape a Large Maze
    • 1037. Valid Boomerang
    • 1038. Binary Search Tree to Greater Sum Tree
    • 1039. Minimum Score Triangulation of Polygon
    • 1040. Moving Stones Until Consecutive II
    • 1041. Robot Bounded In Circle
    • 1042. Flower Planting With No Adjacent
    • 1043. Partition Array for Maximum Sum
    • 1044. Longest Duplicate Substring
    • 1045. Customers Who Bought All Products
    • 1046. Last Stone Weight
    • 1047. Remove All Adjacent Duplicates In String
    • 1048. Longest String Chain
    • 1049. Last Stone Weight II
    • 1050. Actors and Directors Who Cooperated At Least Three Times
    • 1051. Height Checker
    • 1052. Grumpy Bookstore Owner
    • 1053. Previous Permutation With One Swap
    • 1054. Distant Barcodes
    • 1055. Shortest Way to Form String
    • 1056. Confusing Number
    • 1057. Campus Bikes
    • 1058. Minimize Rounding Error to Meet Target
    • 1059. All Paths from Source Lead to Destination
    • 1060. Missing Element in Sorted Array
    • 1061. Lexicographically Smallest Equivalent String
    • 1062. Longest Repeating Substring
    • 1063. Number of Valid Subarrays
    • 1064. Fixed Point
    • 1065. Index Pairs of a String
    • 1066. Campus Bikes II
    • 1067. Digit Count in Range
    • 1068. Product Sales Analysis I
    • 1069. Product Sales Analysis II
    • 1070. Product Sales Analysis III
    • 1071. Greatest Common Divisor of Strings
    • 1072. Flip Columns For Maximum Number of Equal Rows
    • 1073. Adding Two Negabinary Numbers
    • 1074. Number of Submatrices That Sum to Target
    • 1075. Project Employees I
    • 1076. Project Employees II
    • 1077. Project Employees III
    • 1078. Occurrences After Bigram
    • 1079. Letter Tile Possibilities
    • 1080. Insufficient Nodes in Root to Leaf Paths
    • 1081. Smallest Subsequence of Distinct Characters
    • 1082. Sales Analysis I
    • 1083. Sales Analysis II
    • 1084. Sales Analysis III
    • 1085. Sum of Digits in the Minimum Number
    • 1086. High Five
    • 1087. Brace Expansion
    • 1088. Confusing Number II
    • 1089. Duplicate Zeros
    • 1090. Largest Values From Labels
    • 1091. Shortest Path in Binary Matrix
    • 1092. Shortest Common Supersequence
    • 1093. Statistics from a Large Sample
    • 1094. Car Pooling
    • 1095. Find in Mountain Array
    • 1096. Brace Expansion II
    • 1097. Game Play Analysis V
    • 1098. Unpopular Books
    • 1099. Two Sum Less Than K
    • 1100. Find K-Length Substrings With No Repeated Characters
    • 1101. The Earliest Moment When Everyone Become Friends
    • 1102. Path With Maximum Minimum Value
    • 1103. Distribute Candies to People
    • 1104. Path In Zigzag Labelled Binary Tree
    • 1105. Filling Bookcase Shelves
    • 1106. Parsing A Boolean Expression
    • 1107. New Users Daily Count
    • 1108. Defanging an IP Address
    • 1109. Corporate Flight Bookings
    • 1110. Delete Nodes And Return Forest
    • 1111. Maximum Nesting Depth of Two Valid Parentheses Strings
    • 1112. Highest Grade For Each Student
    • 1113. Reported Posts
    • 1114. Print in Order
    • 1115. Print FooBar Alternately
    • 1116. Print Zero Even Odd
    • 1117. Building H2O
    • 1118. Number of Days in a Month
    • 1119. Remove Vowels from a String
    • 1120. Maximum Average Subtree
    • 1121. Divide Array Into Increasing Sequences
    • 1122. Relative Sort Array
    • 1123. Lowest Common Ancestor of Deepest Leaves
    • 1124. Longest Well-Performing Interval
    • 1125. Smallest Sufficient Team
    • 1126. Active Businesses
    • 1127. User Purchase Platform
    • 1128. Number of Equivalent Domino Pairs
    • 1129. Shortest Path with Alternating Colors
    • 1130. Minimum Cost Tree From Leaf Values
    • 1131. Maximum of Absolute Value Expression
    • 1132. Reported Posts II
    • 1133. Largest Unique Number
    • 1134. Armstrong Number
    • 1135. Connecting Cities With Minimum Cost
    • 1136. Parallel Courses
    • 1137. N-th Tribonacci Number
    • 1138. Alphabet Board Path
    • 1139. Largest 1-Bordered Square
    • 1140. Stone Game II
    • 1141. User Activity for the Past 30 Days I
    • 1142. User Activity for the Past 30 Days II
    • 1143. Longest Common Subsequence
    • 1144. Decrease Elements To Make Array Zigzag
    • 1145. Binary Tree Coloring Game
    • 1146. Snapshot Array
    • 1147. Longest Chunked Palindrome Decomposition
    • 1148. Article Views I
    • 1149. Article Views II
    • 1150. Check If a Number Is Majority Element in a Sorted Array
    • 1151. Minimum Swaps to Group All 1's Together
    • 1152. Analyze User Website Visit Pattern
    • 1153. String Transforms Into Another String
    • 1154. Day of the Year
    • 1155. Number of Dice Rolls With Target Sum
    • 1156. Swap For Longest Repeated Character Substring
    • 1157. Online Majority Element In Subarray
    • 1158. Market Analysis I
    • 1159. Market Analysis II
    • 1160. Find Words That Can Be Formed by Characters
    • 1161. Maximum Level Sum of a Binary Tree
    • 1162. As Far from Land as Possible
    • 1163. Last Substring in Lexicographical Order
    • 1164. Product Price at a Given Date
    • 1165. Single-Row Keyboard
    • 1166. Design File System
    • 1167. Minimum Cost to Connect Sticks
    • 1168. Optimize Water Distribution in a Village
    • 1169. Invalid Transactions
    • 1170. Compare Strings by Frequency of the Smallest Character
    • 1171. Remove Zero Sum Consecutive Nodes from Linked List
    • 1172. Dinner Plate Stacks
    • 1173. Immediate Food Delivery I
    • 1174. Immediate Food Delivery II
    • 1175. Prime Arrangements
    • 1176. Diet Plan Performance
    • 1177. Can Make Palindrome from Substring
    • 1178. Number of Valid Words for Each Puzzle
    • 1179. Reformat Department Table
    • 1180. Count Substrings with Only One Distinct Letter
    • 1181. Before and After Puzzle
    • 1182. Shortest Distance to Target Color
    • 1183. Maximum Number of Ones
    • 1184. Distance Between Bus Stops
    • 1185. Day of the Week
    • 1186. Maximum Subarray Sum with One Deletion
    • 1187. Make Array Strictly Increasing
    • 1188. Design Bounded Blocking Queue
    • 1189. Maximum Number of Balloons
    • 1190. Reverse Substrings Between Each Pair of Parentheses
    • 1191. K-Concatenation Maximum Sum
    • 1192. Critical Connections in a Network
    • 1193. Monthly Transactions I
    • 1194. Tournament Winners
    • 1195. Fizz Buzz Multithreaded
    • 1196. How Many Apples Can You Put into the Basket
    • 1197. Minimum Knight Moves
    • 1198. Find Smallest Common Element in All Rows
    • 1199. Minimum Time to Build Blocks
    • 1200. Minimum Absolute Difference
    • 1201. Ugly Number III
    • 1202. Smallest String With Swaps
    • 1203. Sort Items by Groups Respecting Dependencies
    • 1204. Last Person to Fit in the Bus
    • 1205. Monthly Transactions II
    • 1206. Design Skiplist
    • 1207. Unique Number of Occurrences
    • 1208. Get Equal Substrings Within Budget
    • 1209. Remove All Adjacent Duplicates in String II
    • 1210. Minimum Moves to Reach Target with Rotations
    • 1211. Queries Quality and Percentage
    • 1212. Team Scores in Football Tournament
    • 1213. Intersection of Three Sorted Arrays
    • 1214. Two Sum BSTs
    • 1215. Stepping Numbers
    • 1216. Valid Palindrome III
    • 1217. Minimum Cost to Move Chips to The Same Position
    • 1218. Longest Arithmetic Subsequence of Given Difference
    • 1219. Path with Maximum Gold
    • 1220. Count Vowels Permutation
    • 1221. Split a String in Balanced Strings
    • 1222. Queens That Can Attack the King
    • 1223. Dice Roll Simulation
    • 1224. Maximum Equal Frequency
    • 1225. Report Contiguous Dates
    • 1226. The Dining Philosophers
    • 1227. Airplane Seat Assignment Probability
    • 1228. Missing Number In Arithmetic Progression
    • 1229. Meeting Scheduler
    • 1230. Toss Strange Coins
    • 1231. Divide Chocolate
    • 1232. Check If It Is a Straight Line
    • 1233. Remove Sub-Folders from the Filesystem
    • 1234. Replace the Substring for Balanced String
    • 1235. Maximum Profit in Job Scheduling
    • 1236. Web Crawler
    • 1237. Find Positive Integer Solution for a Given Equation
    • 1238. Circular Permutation in Binary Representation
    • 1239. Maximum Length of a Concatenated String with Unique Characters
    • 1240. Tiling a Rectangle with the Fewest Squares
    • 1241. Number of Comments per Post
    • 1242. Web Crawler Multithreaded
    • 1243. Array Transformation
    • 1244. Design A Leaderboard
    • 1245. Tree Diameter
    • 1246. Palindrome Removal
    • 1247. Minimum Swaps to Make Strings Equal
    • 1248. Count Number of Nice Subarrays
    • 1249. Minimum Remove to Make Valid Parentheses
    • 1250. Check If It Is a Good Array
    • 1251. Average Selling Price
    • 1252. Cells with Odd Values in a Matrix
    • 1253. Reconstruct a 2-Row Binary Matrix
    • 1254. Number of Closed Islands
    • 1255. Maximum Score Words Formed by Letters
    • 1256. Encode Number
    • 1257. Smallest Common Region
    • 1258. Synonymous Sentences
    • 1259. Handshakes That Don't Cross
    • 1260. Shift 2D Grid
    • 1261. Find Elements in a Contaminated Binary Tree
    • 1262. Greatest Sum Divisible by Three
    • 1263. Minimum Moves to Move a Box to Their Target Location
    • 1264. Page Recommendations
    • 1265. Print Immutable Linked List in Reverse
    • 1266. Minimum Time Visiting All Points
    • 1267. Count Servers that Communicate
    • 1268. Search Suggestions System
    • 1269. Number of Ways to Stay in the Same Place After Some Steps
    • 1270. All People Report to the Given Manager
    • 1271. Hexspeak
    • 1272. Remove Interval
    • 1273. Delete Tree Nodes
    • 1274. Number of Ships in a Rectangle
    • 1275. Find Winner on a Tic Tac Toe Game
    • 1276. Number of Burgers with No Waste of Ingredients
    • 1277. Count Square Submatrices with All Ones
    • 1278. Palindrome Partitioning III
    • 1279. Traffic Light Controlled Intersection
    • 1280. Students and Examinations
    • 1281. Subtract the Product and Sum of Digits of an Integer
    • 1282. Group the People Given the Group Size They Belong To
    • 1283. Find the Smallest Divisor Given a Threshold
    • 1284. Minimum Number of Flips to Convert Binary Matrix to Zero Matrix
    • 1285. Find the Start and End Number of Continuous Ranges
    • 1286. Iterator for Combination
    • 1287. Element Appearing More Than 25% In Sorted Array
    • 1288. Remove Covered Intervals
    • 1289. Minimum Falling Path Sum II
    • 1290. Convert Binary Number in a Linked List to Integer
    • 1291. Sequential Digits
    • 1292. Maximum Side Length of a Square with Sum Less than or Equal to Threshold
    • 1293. Shortest Path in a Grid with Obstacles Elimination
    • 1294. Weather Type in Each Country
    • 1295. Find Numbers with Even Number of Digits
    • 1296. Divide Array in Sets of K Consecutive Numbers
    • 1297. Maximum Number of Occurrences of a Substring
    • 1298. Maximum Candies You Can Get from Boxes
    • 1299. Replace Elements with Greatest Element on Right Side
    • 1300. Sum of Mutated Array Closest to Target
    • 1301. Number of Paths with Max Score
    • 1302. Deepest Leaves Sum
    • 1303. Find the Team Size
    • 1304. Find N Unique Integers Sum up to Zero
    • 1305. All Elements in Two Binary Search Trees
    • 1306. Jump Game III
    • 1307. Verbal Arithmetic Puzzle
    • 1308. Running Total for Different Genders
    • 1309. Decrypt String from Alphabet to Integer Mapping
    • 1310. XOR Queries of a Subarray
    • 1311. Get Watched Videos by Your Friends
    • 1312. Minimum Insertion Steps to Make a String Palindrome
    • 1313. Decompress Run-Length Encoded List
    • 1314. Matrix Block Sum
    • 1315. Sum of Nodes with Even-Valued Grandparent
    • 1316. Distinct Echo Substrings
    • 1317. Convert Integer to the Sum of Two No-Zero Integers
    • 1318. Minimum Flips to Make a OR b Equal to c
    • 1319. Number of Operations to Make Network Connected
    • 1320. Minimum Distance to Type a Word Using Two Fingers
    • 1321. Restaurant Growth
    • 1322. Ads Performance
    • 1323. Maximum 69 Number
    • 1324. Print Words Vertically
    • 1325. Delete Leaves With a Given Value
    • 1326. Minimum Number of Taps to Open to Water a Garden
    • 1327. List the Products Ordered in a Period
    • 1328. Break a Palindrome
    • 1329. Sort the Matrix Diagonally
    • 1330. Reverse Subarray To Maximize Array Value
    • 1331. Rank Transform of an Array
    • 1332. Remove Palindromic Subsequences
    • 1333. Filter Restaurants by Vegan-Friendly, Price and Distance
    • 1334. Find the City With the Smallest Number of Neighbors at a Threshold Distance
    • 1335. Minimum Difficulty of a Job Schedule
    • 1336. Number of Transactions per Visit
    • 1337. The K Weakest Rows in a Matrix
    • 1338. Reduce Array Size to The Half
    • 1339. Maximum Product of Splitted Binary Tree
    • 1340. Jump Game V
    • 1341. Movie Rating
    • 1342. Number of Steps to Reduce a Number to Zero
    • 1343. Number of Sub-arrays of Size K and Average Greater than or Equal to Threshold
    • 1344. Angle Between Hands of a Clock
    • 1345. Jump Game IV
    • 1346. Check If N and Its Double Exist
    • 1347. Minimum Number of Steps to Make Two Strings Anagram
    • 1348. Tweet Counts Per Frequency
    • 1349. Maximum Students Taking Exam
    • 1350. Students With Invalid Departments
    • 1351. Count Negative Numbers in a Sorted Matrix
    • 1352. Product of the Last K Numbers
    • 1353. Maximum Number of Events That Can Be Attended
    • 1354. Construct Target Array With Multiple Sums
    • 1355. Activity Participants
    • 1356. Sort Integers by The Number of 1 Bits
    • 1357. Apply Discount Every n Orders
    • 1358. Number of Substrings Containing All Three Characters
    • 1359. Count All Valid Pickup and Delivery Options
    • 1360. Number of Days Between Two Dates
    • 1361. Validate Binary Tree Nodes
    • 1362. Closest Divisors
    • 1363. Largest Multiple of Three
    • 1364. Number of Trusted Contacts of a Customer
    • 1365. How Many Numbers Are Smaller Than the Current Number
    • 1366. Rank Teams by Votes
    • 1367. Linked List in Binary Tree
    • 1368. Minimum Cost to Make at Least One Valid Path in a Grid
    • 1369. Get the Second Most Recent Activity
    • 1370. Increasing Decreasing String
    • 1371. Find the Longest Substring Containing Vowels in Even Counts
    • 1372. Longest ZigZag Path in a Binary Tree
    • 1373. Maximum Sum BST in Binary Tree
    • 1374. Generate a String With Characters That Have Odd Counts
    • 1375. Bulb Switcher III
    • 1376. Time Needed to Inform All Employees
    • 1377. Frog Position After T Seconds
    • 1378. Replace Employee ID With The Unique Identifier
    • 1379. Find a Corresponding Node of a Binary Tree in a Clone of That Tree
    • 1380. Lucky Numbers in a Matrix
    • 1381. Design a Stack With Increment Operation
    • 1382. Balance a Binary Search Tree
    • 1383. Maximum Performance of a Team
    • 1384. Total Sales Amount by Year
    • 1385. Find the Distance Value Between Two Arrays
    • 1386. Cinema Seat Allocation
    • 1387. Sort Integers by The Power Value
    • 1388. Pizza With 3n Slices
    • 1389. Create Target Array in the Given Order
    • 1390. Four Divisors
    • 1391. Check if There is a Valid Path in a Grid
    • 1392. Longest Happy Prefix
    • 1393. Capital Gain/Loss
    • 1394. Find Lucky Integer in an Array
    • 1395. Count Number of Teams
    • 1396. Design Underground System
    • 1397. Find All Good Strings
    • 1398. Customers Who Bought Products A and B but Not C
    • 1399. Count Largest Group
    • 1400. Construct K Palindrome Strings
    • 1401. Circle and Rectangle Overlapping
    • 1402. Reducing Dishes
    • 1403. Minimum Subsequence in Non-Increasing Order
    • 1404. Number of Steps to Reduce a Number in Binary Representation to One
    • 1405. Longest Happy String
    • 1406. Stone Game III
    • 1407. Top Travellers
    • 1408. String Matching in an Array
    • 1409. Queries on a Permutation With Key
    • 1410. HTML Entity Parser
    • 1411. Number of Ways to Paint N × 3 Grid
    • 1412. Find the Quiet Students in All Exams
    • 1413. Minimum Value to Get Positive Step by Step Sum
    • 1414. Find the Minimum Number of Fibonacci Numbers Whose Sum Is K
    • 1415. The k-th Lexicographical String of All Happy Strings of Length n
    • 1416. Restore The Array
    • 1417. Reformat The String
    • 1418. Display Table of Food Orders in a Restaurant
    • 1419. Minimum Number of Frogs Croaking
    • 1420. Build Array Where You Can Find The Maximum Exactly K Comparisons
    • 1421. NPV Queries
    • 1422. Maximum Score After Splitting a String
    • 1423. Maximum Points You Can Obtain from Cards
    • 1424. Diagonal Traverse II
    • 1425. Constrained Subsequence Sum
    • 1426. Counting Elements
    • 1427. Perform String Shifts
    • 1428. Leftmost Column with at Least a One
    • 1429. First Unique Number
    • 1430. Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree
    • 1431. Kids With the Greatest Number of Candies
    • 1432. Max Difference You Can Get From Changing an Integer
    • 1433. Check If a String Can Break Another String
    • 1434. Number of Ways to Wear Different Hats to Each Other
    • 1435. Create a Session Bar Chart
    • 1436. Destination City
    • 1437. Check If All 1's Are at Least Length K Places Away
    • 1438. Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit
    • 1439. Find the Kth Smallest Sum of a Matrix With Sorted Rows
    • 1440. Evaluate Boolean Expression
    • 1441. Build an Array With Stack Operations
    • 1442. Count Triplets That Can Form Two Arrays of Equal XOR
    • 1443. Minimum Time to Collect All Apples in a Tree
    • 1444. Number of Ways of Cutting a Pizza
    • 1445. Apples & Oranges
    • 1446. Consecutive Characters
    • 1447. Simplified Fractions
    • 1448. Count Good Nodes in Binary Tree
    • 1449. Form Largest Integer With Digits That Add up to Target
    • 1450. Number of Students Doing Homework at a Given Time
    • 1451. Rearrange Words in a Sentence
    • 1452. People Whose List of Favorite Companies Is Not a Subset of Another List
    • 1453. Maximum Number of Darts Inside of a Circular Dartboard
    • 1454. Active Users
    • 1455. Check If a Word Occurs As a Prefix of Any Word in a Sentence
    • 1456. Maximum Number of Vowels in a Substring of Given Length
    • 1457. Pseudo-Palindromic Paths in a Binary Tree
    • 1458. Max Dot Product of Two Subsequences
    • 1459. Rectangles Area
    • 1460. Make Two Arrays Equal by Reversing Sub-arrays
    • 1461. Check If a String Contains All Binary Codes of Size K
    • 1462. Course Schedule IV
    • 1463. Cherry Pickup II
    • 1464. Maximum Product of Two Elements in an Array
    • 1465. Maximum Area of a Piece of Cake After Horizontal and Vertical Cuts
    • 1466. Reorder Routes to Make All Paths Lead to the City Zero
    • 1467. Probability of a Two Boxes Having The Same Number of Distinct Balls
    • 1468. Calculate Salaries
    • 1469. Find All The Lonely Nodes
    • 1470. Shuffle the Array
    • 1471. The k Strongest Values in an Array
    • 1472. Design Browser History
    • 1473. Paint House III
    • 1474. Delete N Nodes After M Nodes of a Linked List
    • 1475. Final Prices With a Special Discount in a Shop
    • 1476. Subrectangle Queries
    • 1477. Find Two Non-overlapping Sub-arrays Each With Target Sum
    • 1478. Allocate Mailboxes
    • 1479. Sales by Day of the Week
    • 1480. Running Sum of 1d Array
    • 1481. Least Number of Unique Integers after K Removals
    • 1482. Minimum Number of Days to Make m Bouquets
    • 1483. Kth Ancestor of a Tree Node
    • 1484. Group Sold Products By The Date
    • 1485. Clone Binary Tree With Random Pointer
    • 1486. XOR Operation in an Array
    • 1487. Making File Names Unique
    • 1488. Avoid Flood in The City
    • 1489. Find Critical and Pseudo-Critical Edges in Minimum Spanning Tree
    • 1490. Clone N-ary Tree
    • 1491. Average Salary Excluding the Minimum and Maximum Salary
    • 1492. The kth Factor of n
    • 1493. Longest Subarray of 1's After Deleting One Element
    • 1494. Parallel Courses II
    • 1495. Friendly Movies Streamed Last Month
    • 1496. Path Crossing
    • 1497. Check If Array Pairs Are Divisible by k
    • 1498. Number of Subsequences That Satisfy the Given Sum Condition
    • 1499. Max Value of Equation
    • 1500. Design a File Sharing System
    • 1501. Countries You Can Safely Invest In
    • 1502. Can Make Arithmetic Progression From Sequence
    • 1503. Last Moment Before All Ants Fall Out of a Plank
    • 1504. Count Submatrices With All Ones
    • 1505. Minimum Possible Integer After at Most K Adjacent Swaps On Digits
    • 1506. Find Root of N-Ary Tree
    • 1507. Reformat Date
    • 1508. Range Sum of Sorted Subarray Sums
    • 1509. Minimum Difference Between Largest and Smallest Value in Three Moves
    • 1510. Stone Game IV
    • 1511. Customer Order Frequency
    • 1512. Number of Good Pairs
    • 1513. Number of Substrings With Only 1s
    • 1514. Path with Maximum Probability
    • 1515. Best Position for a Service Centre
    • 1516. Move Sub-Tree of N-Ary Tree
    • 1517. Find Users With Valid E-Mails
    • 1518. Water Bottles
    • 1519. Number of Nodes in the Sub-Tree With the Same Label
    • 1520. Maximum Number of Non-Overlapping Substrings
    • 1521. Find a Value of a Mysterious Function Closest to Target
    • 1522. Diameter of N-Ary Tree
    • 1523. Count Odd Numbers in an Interval Range
    • 1524. Number of Sub-arrays With Odd Sum
    • 1525. Number of Good Ways to Split a String
    • 1526. Minimum Number of Increments on Subarrays to Form a Target Array
    • 1527. Patients With a Condition
    • 1528. Shuffle String
    • 1529. Bulb Switcher IV
    • 1530. Number of Good Leaf Nodes Pairs
    • 1531. String Compression II
    • 1532. The Most Recent Three Orders
    • 1533. Find the Index of the Large Integer
    • 1534. Count Good Triplets
    • 1535. Find the Winner of an Array Game
    • 1536. Minimum Swaps to Arrange a Binary Grid
    • 1537. Get the Maximum Score
    • 1538. Guess the Majority in a Hidden Array
    • 1539. Kth Missing Positive Number
    • 1540. Can Convert String in K Moves
    • 1541. Minimum Insertions to Balance a Parentheses String
    • 1542. Find Longest Awesome Substring
    • 1543. Fix Product Name Format
    • 1544. Make The String Great
    • 1545. Find Kth Bit in Nth Binary String
    • 1546. Maximum Number of Non-Overlapping Subarrays With Sum Equals Target
    • 1547. Minimum Cost to Cut a Stick
    • 1548. The Most Similar Path in a Graph
    • 1549. The Most Recent Orders for Each Product
    • 1550. Three Consecutive Odds
    • 1551. Minimum Operations to Make Array Equal
    • 1552. Magnetic Force Between Two Balls
    • 1553. Minimum Number of Days to Eat N Oranges
    • 1554. Strings Differ by One Character
    • 1555. Bank Account Summary
    • 1556. Thousand Separator
    • 1557. Minimum Number of Vertices to Reach All Nodes
    • 1558. Minimum Numbers of Function Calls to Make Target Array
    • 1559. Detect Cycles in 2D Grid
    • 1560. Most Visited Sector in a Circular Track
    • 1561. Maximum Number of Coins You Can Get
    • 1562. Find Latest Group of Size M
    • 1563. Stone Game V
    • 1564. Put Boxes Into the Warehouse I
    • 1565. Unique Orders and Customers Per Month
    • 1566. Detect Pattern of Length M Repeated K or More Times
    • 1567. Maximum Length of Subarray With Positive Product
    • 1568. Minimum Number of Days to Disconnect Island
    • 1569. Number of Ways to Reorder Array to Get Same BST
    • 1570. Dot Product of Two Sparse Vectors
    • 1571. Warehouse Manager
    • 1572. Matrix Diagonal Sum
    • 1573. Number of Ways to Split a String
    • 1574. Shortest Subarray to be Removed to Make Array Sorted
    • 1575. Count All Possible Routes
    • 1576. Replace All ?'s to Avoid Consecutive Repeating Characters
    • 1577. Number of Ways Where Square of Number Is Equal to Product of Two Numbers
    • 1578. Minimum Deletion Cost to Avoid Repeating Letters
    • 1579. Remove Max Number of Edges to Keep Graph Fully Traversable
    • 1580. Put Boxes Into the Warehouse II
    • 1581. Customer Who Visited but Did Not Make Any Transactions
    • 1582. Special Positions in a Binary Matrix
    • 1583. Count Unhappy Friends
    • 1584. Min Cost to Connect All Points
    • 1585. Check If String Is Transformable With Substring Sort Operations
    • 1586. Binary Search Tree Iterator II
    • 1587. Bank Account Summary II
    • 1588. Sum of All Odd Length Subarrays
    • 1589. Maximum Sum Obtained of Any Permutation
    • 1590. Make Sum Divisible by P
    • 1591. Strange Printer II
    • 1592. Rearrange Spaces Between Words
    • 1593. Split a String Into the Max Number of Unique Substrings
    • 1594. Maximum Non Negative Product in a Matrix
    • 1595. Minimum Cost to Connect Two Groups of Points
    • 1596. The Most Frequently Ordered Products for Each Customer
    • 1597. Build Binary Expression Tree From Infix Expression
    • 1598. Crawler Log Folder
    • 1599. Maximum Profit of Operating a Centennial Wheel
    • 1600. Throne Inheritance
    • 1601. Maximum Number of Achievable Transfer Requests
    • 1602. Find Nearest Right Node in Binary Tree
    • 1603. Design Parking System
    • 1604. Alert Using Same Key-Card Three or More Times in a One Hour Period
    • 1605. Find Valid Matrix Given Row and Column Sums
    • 1606. Find Servers That Handled Most Number of Requests
    • 1607. Sellers With No Sales
    • 1608. Special Array With X Elements Greater Than or Equal X
    • 1609. Even Odd Tree
    • 1610. Maximum Number of Visible Points
    • 1611. Minimum One Bit Operations to Make Integers Zero
    • 1612. Check If Two Expression Trees are Equivalent
    • 1613. Find the Missing IDs
    • 1614. Maximum Nesting Depth of the Parentheses
    • 1615. Maximal Network Rank
    • 1616. Split Two Strings to Make Palindrome
    • 1617. Count Subtrees With Max Distance Between Cities
    • 1618. Maximum Font to Fit a Sentence in a Screen
    • 1619. Mean of Array After Removing Some Elements
    • 1620. Coordinate With Maximum Network Quality
    • 1621. Number of Sets of K Non-Overlapping Line Segments
    • 1622. Fancy Sequence
    • 1623. All Valid Triplets That Can Represent a Country
    • 1624. Largest Substring Between Two Equal Characters
    • 1625. Lexicographically Smallest String After Applying Operations
    • 1626. Best Team With No Conflicts
    • 1627. Graph Connectivity With Threshold
    • 1628. Design an Expression Tree With Evaluate Function
    • 1629. Slowest Key
    • 1630. Arithmetic Subarrays
    • 1631. Path With Minimum Effort
    • 1632. Rank Transform of a Matrix
    • 1633. Percentage of Users Attended a Contest
    • 1634. Add Two Polynomials Represented as Linked Lists
    • 1635. Hopper Company Queries I
    • 1636. Sort Array by Increasing Frequency
    • 1637. Widest Vertical Area Between Two Points Containing No Points
    • 1638. Count Substrings That Differ by One Character
    • 1639. Number of Ways to Form a Target String Given a Dictionary
    • 1640. Check Array Formation Through Concatenation
    • 1641. Count Sorted Vowel Strings
    • 1642. Furthest Building You Can Reach
    • 1643. Kth Smallest Instructions
    • 1644. Lowest Common Ancestor of a Binary Tree II
    • 1645. Hopper Company Queries II
    • 1646. Get Maximum in Generated Array
    • 1647. Minimum Deletions to Make Character Frequencies Unique
    • 1648. Sell Diminishing-Valued Colored Balls
    • 1649. Create Sorted Array through Instructions
    • 1650. Lowest Common Ancestor of a Binary Tree III
    • 1651. Hopper Company Queries III
    • 1652. Defuse the Bomb
    • 1653. Minimum Deletions to Make String Balanced
    • 1654. Minimum Jumps to Reach Home
    • 1655. Distribute Repeating Integers
    • 1656. Design an Ordered Stream
    • 1657. Determine if Two Strings Are Close
    • 1658. Minimum Operations to Reduce X to Zero
    • 1659. Maximize Grid Happiness
    • 1660. Correct a Binary Tree
    • 1661. Average Time of Process per Machine
    • 1662. Check If Two String Arrays are Equivalent
    • 1663. Smallest String With A Given Numeric Value
    • 1664. Ways to Make a Fair Array
    • 1665. Minimum Initial Energy to Finish Tasks
    • 1666. Change the Root of a Binary Tree
    • 1667. Fix Names in a Table
    • 1668. Maximum Repeating Substring
    • 1669. Merge In Between Linked Lists
    • 1670. Design Front Middle Back Queue
    • 1671. Minimum Number of Removals to Make Mountain Array
    • 1672. Richest Customer Wealth
    • 1673. Find the Most Competitive Subsequence
    • 1674. Minimum Moves to Make Array Complementary
    • 1675. Minimize Deviation in Array
    • 1676. Lowest Common Ancestor of a Binary Tree IV
    • 1677. Product's Worth Over Invoices
    • 1678. Goal Parser Interpretation
    • 1679. Max Number of K-Sum Pairs
    • 1680. Concatenation of Consecutive Binary Numbers
    • 1681. Minimum Incompatibility
    • 1682. Longest Palindromic Subsequence II
    • 1683. Invalid Tweets
    • 1684. Count the Number of Consistent Strings
    • 1685. Sum of Absolute Differences in a Sorted Array
    • 1686. Stone Game VI
    • 1687. Delivering Boxes from Storage to Ports
    • 1688. Count of Matches in Tournament
    • 1689. Partitioning Into Minimum Number Of Deci-Binary Numbers
    • 1690. Stone Game VII
    • 1691. Maximum Height by Stacking Cuboids
    • 1692. Count Ways to Distribute Candies
    • 1693. Daily Leads and Partners
    • 1694. Reformat Phone Number
    • 1695. Maximum Erasure Value
    • 1696. Jump Game VI
    • 1697. Checking Existence of Edge Length Limited Paths
    • 1698. Number of Distinct Substrings in a String
    • 1699. Number of Calls Between Two Persons
    • 1700. Number of Students Unable to Eat Lunch
    • 1701. Average Waiting Time
    • 1702. Maximum Binary String After Change
    • 1703. Minimum Adjacent Swaps for K Consecutive Ones
    • 1704. Determine if String Halves Are Alike
    • 1705. Maximum Number of Eaten Apples
    • 1706. Where Will the Ball Fall
    • 1707. Maximum XOR With an Element From Array
    • 1708. Largest Subarray Length K
    • 1709. Biggest Window Between Visits
    • 1710. Maximum Units on a Truck
    • 1711. Count Good Meals
    • 1712. Ways to Split Array Into Three Subarrays
    • 1713. Minimum Operations to Make a Subsequence
    • 1714. Sum Of Special Evenly-Spaced Elements In Array
    • 1715. Count Apples and Oranges
    • 1716. Calculate Money in Leetcode Bank
    • 1717. Maximum Score From Removing Substrings
    • 1718. Construct the Lexicographically Largest Valid Sequence
    • 1719. Number Of Ways To Reconstruct A Tree
    • 1720. Decode XORed Array
    • 1721. Swapping Nodes in a Linked List
    • 1722. Minimize Hamming Distance After Swap Operations
    • 1723. Find Minimum Time to Finish All Jobs
    • 1724. Checking Existence of Edge Length Limited Paths II
    • 1725. Number Of Rectangles That Can Form The Largest Square
    • 1726. Tuple with Same Product
    • 1727. Largest Submatrix With Rearrangements
    • 1728. Cat and Mouse II
    • 1729. Find Followers Count
    • 1730. Shortest Path to Get Food
    • 1731. The Number of Employees Which Report to Each Employee
    • 1732. Find the Highest Altitude
    • 1733. Minimum Number of People to Teach
    • 1734. Decode XORed Permutation
    • 1735. Count Ways to Make Array With Product
    • 1736. Latest Time by Replacing Hidden Digits
    • 1737. Change Minimum Characters to Satisfy One of Three Conditions
    • 1738. Find Kth Largest XOR Coordinate Value
    • 1739. Building Boxes
    • 1740. Find Distance in a Binary Tree
    • 1741. Find Total Time Spent by Each Employee
    • 1742. Maximum Number of Balls in a Box
    • 1743. Restore the Array From Adjacent Pairs
    • 1744. Can You Eat Your Favorite Candy on Your Favorite Day?
    • 1745. Palindrome Partitioning IV
    • 1746. Maximum Subarray Sum After One Operation
    • 1747. Leetflex Banned Accounts
    • 1748. Sum of Unique Elements
    • 1749. Maximum Absolute Sum of Any Subarray
    • 1750. Minimum Length of String After Deleting Similar Ends
    • 1751. Maximum Number of Events That Can Be Attended II
    • 1752. Check if Array Is Sorted and Rotated
    • 1753. Maximum Score From Removing Stones
    • 1754. Largest Merge Of Two Strings
    • 1755. Closest Subsequence Sum
    • 1756. Design Most Recently Used Queue
    • 1757. Recyclable and Low Fat Products
    • 1758. Minimum Changes To Make Alternating Binary String
    • 1759. Count Number of Homogenous Substrings
    • 1760. Minimum Limit of Balls in a Bag
    • 1761. Minimum Degree of a Connected Trio in a Graph
    • 1762. Buildings With an Ocean View
    • 1763. Longest Nice Substring
    • 1764. Form Array by Concatenating Subarrays of Another Array
    • 1765. Map of Highest Peak
    • 1766. Tree of Coprimes
    • 1767. Find the Subtasks That Did Not Execute
    • 1768. Merge Strings Alternately
    • 1769. Minimum Number of Operations to Move All Balls to Each Box
    • 1770. Maximum Score from Performing Multiplication Operations
    • 1771. Maximize Palindrome Length From Subsequences
    • 1772. Sort Features by Popularity
    • 1773. Count Items Matching a Rule
    • 1774. Closest Dessert Cost
    • 1775. Equal Sum Arrays With Minimum Number of Operations
    • 1776. Car Fleet II
    • 1777. Product's Price for Each Store
    • 1778. Shortest Path in a Hidden Grid
    • 1779. Find Nearest Point That Has the Same X or Y Coordinate
    • 1780. Check if Number is a Sum of Powers of Three
    • 1781. Sum of Beauty of All Substrings
    • 1782. Count Pairs Of Nodes
    • 1783. Grand Slam Titles
    • 1784. Check if Binary String Has at Most One Segment of Ones
    • 1785. Minimum Elements to Add to Form a Given Sum
    • 1786. Number of Restricted Paths From First to Last Node
    • 1787. Make the XOR of All Segments Equal to Zero
    • 1788. Maximize the Beauty of the Garden
    • 1789. Primary Department for Each Employee
    • 1790. Check if One String Swap Can Make Strings Equal
    • 1791. Find Center of Star Graph
    • 1792. Maximum Average Pass Ratio
    • 1793. Maximum Score of a Good Subarray
    • 1794. Count Pairs of Equal Substrings With Minimum Difference
    • 1795. Rearrange Products Table
    • 1796. Second Largest Digit in a String
    • 1797. Design Authentication Manager
    • 1798. Maximum Number of Consecutive Values You Can Make
    • 1799. Maximize Score After N Operations
    • 1800. Maximum Ascending Subarray Sum
    • 1801. Number of Orders in the Backlog
    • 1802. Maximum Value at a Given Index in a Bounded Array
    • 1803. Count Pairs With XOR in a Range
    • 1804. Implement Trie II (solutions/Prefix Tree)
    • 1805. Number of Different Integers in a String
    • 1806. Minimum Number of Operations to Reinitialize a Permutation
    • 1807. Evaluate the Bracket Pairs of a String
    • 1808. Maximize Number of Nice Divisors
    • 1809. Ad-Free Sessions
    • 1810. Minimum Path Cost in a Hidden Grid
    • 1811. Find Interview Candidates
    • 1812. Determine Color of a Chessboard Square
    • 1813. Sentence Similarity III
    • 1814. Count Nice Pairs in an Array
    • 1815. Maximum Number of Groups Getting Fresh Donuts
    • 1816. Truncate Sentence
    • 1817. Finding the Users Active Minutes
    • 1818. Minimum Absolute Sum Difference
    • 1819. Number of Different Subsequences GCDs
    • 1820. Maximum Number of Accepted Invitations
    • 1821. Find Customers With Positive Revenue this Year
    • 1822. Sign of the Product of an Array
    • 1823. Find the Winner of the Circular Game
    • 1824. Minimum Sideway Jumps
    • 1825. Finding MK Average
    • 1826. Faulty Sensor
    • 1827. Minimum Operations to Make the Array Increasing
    • 1828. Queries on Number of Points Inside a Circle
    • 1829. Maximum XOR for Each Query
    • 1830. Minimum Number of Operations to Make String Sorted
    • 1831. Maximum Transaction Each Day
    • 1832. Check if the Sentence Is Pangram
    • 1833. Maximum Ice Cream Bars
    • 1834. Single-Threaded CPU
    • 1835. Find XOR Sum of All Pairs Bitwise AND
    • 1836. Remove Duplicates From an Unsorted Linked List
    • 1837. Sum of Digits in Base K
    • 1838. Frequency of the Most Frequent Element
    • 1839. Longest Substring Of All Vowels in Order
    • 1840. Maximum Building Height
    • 1841. League Statistics
    • 1842. Next Palindrome Using Same Digits
    • 1843. Suspicious Bank Accounts
    • 1844. Replace All Digits with Characters
    • 1845. Seat Reservation Manager
    • 1846. Maximum Element After Decreasing and Rearranging
    • 1847. Closest Room
    • 1848. Minimum Distance to the Target Element
    • 1849. Splitting a String Into Descending Consecutive Values
    • 1850. Minimum Adjacent Swaps to Reach the Kth Smallest Number
    • 1851. Minimum Interval to Include Each Query
    • 1852. Distinct Numbers in Each Subarray
    • 1853. Convert Date Format
    • 1854. Maximum Population Year
    • 1855. Maximum Distance Between a Pair of Values
    • 1856. Maximum Subarray Min-Product
    • 1857. Largest Color Value in a Directed Graph
    • 1858. Longest Word With All Prefixes
    • 1859. Sorting the Sentence
    • 1860. Incremental Memory Leak
    • 1861. Rotating the Box
    • 1862. Sum of Floored Pairs
    • 1863. Sum of All Subset XOR Totals
    • 1864. Minimum Number of Swaps to Make the Binary String Alternating
    • 1865. Finding Pairs With a Certain Sum
    • 1866. Number of Ways to Rearrange Sticks With K Sticks Visible
    • 1867. Orders With Maximum Quantity Above Average
    • 1868. Product of Two Run-Length Encoded Arrays
    • 1869. Longer Contiguous Segments of Ones than Zeros
    • 1870. Minimum Speed to Arrive on Time
    • 1871. Jump Game VII
    • 1872. Stone Game VIII
    • 1873. Calculate Special Bonus
    • 1874. Minimize Product Sum of Two Arrays
    • 1875. Group Employees of the Same Salary
    • 1876. Substrings of Size Three with Distinct Characters
    • 1877. Minimize Maximum Pair Sum in Array
    • 1878. Get Biggest Three Rhombus Sums in a Grid
    • 1879. Minimum XOR Sum of Two Arrays
    • 1880. Check if Word Equals Summation of Two Words
    • 1881. Maximum Value after Insertion
    • 1882. Process Tasks Using Servers
    • 1883. Minimum Skips to Arrive at Meeting On Time
    • 1884. Egg Drop With 2 Eggs and N Floors
    • 1885. Count Pairs in Two Arrays
    • 1886. Determine Whether Matrix Can Be Obtained By Rotation
    • 1887. Reduction Operations to Make the Array Elements Equal
    • 1888. Minimum Number of Flips to Make the Binary String Alternating
    • 1889. Minimum Space Wasted From Packaging
    • 1890. The Latest Login in 2020
    • 1891. Cutting Ribbons
    • 1892. Page Recommendations II
    • 1893. Check if All the Integers in a Range Are Covered
    • 1894. Find the Student that Will Replace the Chalk
    • 1895. Largest Magic Square
    • 1896. Minimum Cost to Change the Final Value of Expression
    • 1897. Redistribute Characters to Make All Strings Equal
    • 1898. Maximum Number of Removable Characters
    • 1899. Merge Triplets to Form Target Triplet
    • 1900. The Earliest and Latest Rounds Where Players Compete
    • 1901. Find a Peak Element II
    • 1902. Depth of BST Given Insertion Order
    • 1903. Largest Odd Number in String
    • 1904. The Number of Full Rounds You Have Played
    • 1905. Count Sub Islands
    • 1906. Minimum Absolute Difference Queries
    • 1907. Count Salary Categories
    • 1908. Game of Nim
    • 1909. Remove One Element to Make the Array Strictly Increasing
    • 1910. Remove All Occurrences of a Substring
    • 1911. Maximum Alternating Subsequence Sum
    • 1912. Design Movie Rental System
    • 1913. Maximum Product Difference Between Two Pairs
    • 1914. Cyclically Rotating a Grid
    • 1915. Number of Wonderful Substrings
    • 1916. Count Ways to Build Rooms in an Ant Colony
    • 1917. Leetcodify Friends Recommendations
    • 1918. Kth Smallest Subarray Sum
    • 1919. Leetcodify Similar Friends
    • 1920. Build Array from Permutation
    • 1921. Eliminate Maximum Number of Monsters
    • 1922. Count Good Numbers
    • 1923. Longest Common Subpath
    • 1924. Erect the Fence II
    • 1925. Count Square Sum Triples
    • 1926. Nearest Exit from Entrance in Maze
    • 1927. Sum Game
    • 1928. Minimum Cost to Reach Destination in Time
    • 1929. Concatenation of Array
    • 1930. Unique Length-3 Palindromic Subsequences
    • 1931. Painting a Grid With Three Different Colors
    • 1932. Merge BSTs to Create Single BST
    • 1933. Check if String Is Decomposable Into Value-Equal Substrings
    • 1934. Confirmation Rate
    • 1935. Maximum Number of Words You Can Type
    • 1936. Add Minimum Number of Rungs
    • 1937. Maximum Number of Points with Cost
    • 1938. Maximum Genetic Difference Query
    • 1939. Users That Actively Request Confirmation Messages
    • 1940. Longest Common Subsequence Between Sorted Arrays
    • 1941. Check if All Characters Have Equal Number of Occurrences
    • 1942. The Number of the Smallest Unoccupied Chair
    • 1943. Describe the Painting
    • 1944. Number of Visible People in a Queue
    • 1945. Sum of Digits of String After Convert
    • 1946. Largest Number After Mutating Substring
    • 1947. Maximum Compatibility Score Sum
    • 1948. Delete Duplicate Folders in System
    • 1949. Strong Friendship
    • 1950. Maximum of Minimum Values in All Subarrays
    • 1951. All the Pairs With the Maximum Number of Common Followers
    • 1952. Three Divisors
    • 1953. Maximum Number of Weeks for Which You Can Work
    • 1954. Minimum Garden Perimeter to Collect Enough Apples
    • 1955. Count Number of Special Subsequences
    • 1956. Minimum Time For K Virus Variants to Spread
    • 1957. Delete Characters to Make Fancy String
    • 1958. Check if Move is Legal
    • 1959. Minimum Total Space Wasted With K Resizing Operations
    • 1960. Maximum Product of the Length of Two Palindromic Substrings
    • 1961. Check If String Is a Prefix of Array
    • 1962. Remove Stones to Minimize the Total
    • 1963. Minimum Number of Swaps to Make the String Balanced
    • 1964. Find the Longest Valid Obstacle Course at Each Position
    • 1965. Employees With Missing Information
    • 1966. Binary Searchable Numbers in an Unsorted Array
    • 1967. Number of Strings That Appear as Substrings in Word
    • 1968. Array With Elements Not Equal to Average of Neighbors
    • 1969. Minimum Non-Zero Product of the Array Elements
    • 1970. Last Day Where You Can Still Cross
    • 1971. Find if Path Exists in Graph
    • 1972. First and Last Call On the Same Day
    • 1973. Count Nodes Equal to Sum of Descendants
    • 1974. Minimum Time to Type Word Using Special Typewriter
    • 1975. Maximum Matrix Sum
    • 1976. Number of Ways to Arrive at Destination
    • 1977. Number of Ways to Separate Numbers
    • 1978. Employees Whose Manager Left the Company
    • 1979. Find Greatest Common Divisor of Array
    • 1980. Find Unique Binary String
    • 1981. Minimize the Difference Between Target and Chosen Elements
    • 1982. Find Array Given Subset Sums
    • 1983. Widest Pair of Indices With Equal Range Sum
    • 1984. Minimum Difference Between Highest and Lowest of K Scores
    • 1985. Find the Kth Largest Integer in the Array
    • 1986. Minimum Number of Work Sessions to Finish the Tasks
    • 1987. Number of Unique Good Subsequences
    • 1988. Find Cutoff Score for Each School
    • 1989. Maximum Number of People That Can Be Caught in Tag
    • 1990. Count the Number of Experiments
    • 1991. Find the Middle Index in Array
    • 1992. Find All Groups of Farmland
    • 1993. Operations on Tree
    • 1994. The Number of Good Subsets
    • 1995. Count Special Quadruplets
    • 1996. The Number of Weak Characters in the Game
    • 1997. First Day Where You Have Been in All the Rooms
    • 1998. GCD Sort of an Array
    • 1999. Smallest Greater Multiple Made of Two Digits
    • 2000. Reverse Prefix of Word
    • 2001. Number of Pairs of Interchangeable Rectangles
    • 2002. Maximum Product of the Length of Two Palindromic Subsequences
    • 2003. Smallest Missing Genetic Value in Each Subtree
    • 2004. The Number of Seniors and Juniors to Join the Company
    • 2005. Subtree Removal Game with Fibonacci Tree
    • 2006. Count Number of Pairs With Absolute Difference K
    • 2007. Find Original Array From Doubled Array
    • 2008. Maximum Earnings From Taxi
    • 2009. Minimum Number of Operations to Make Array Continuous
    • 2010. The Number of Seniors and Juniors to Join the Company II
    • 2011. Final Value of Variable After Performing Operations
    • 2012. Sum of Beauty in the Array
    • 2013. Detect Squares
    • 2014. Longest Subsequence Repeated k Times
    • 2015. Average Height of Buildings in Each Segment
    • 2016. Maximum Difference Between Increasing Elements
    • 2017. Grid Game
    • 2018. Check if Word Can Be Placed In Crossword
    • 2019. The Score of Students Solving Math Expression
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  • 4S Analysis
  • Design Load Balancer
  • Top K Frequent Elements in Recent X mins
  • Design TinyURL
  • Design Twitter
  • Design Instagram
  • Design Web Crawler
  • Resources
  • Blogs
  • Website
  • Video

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System Design

Topics

  • News feed

  • Job scheduler

4S Analysis

  • Scenario Clarify: requirements, features, QPS, DAU, interface

  • Service Break down into small services/model

  • Storage Database, data schema

    • SQL database: user table

    • NoSQL database: Social Graph

    • File system: Media files, documents

  • Scale

    Sharding, optimization

Design Load Balancer

Round Robin Weighted round robin Least connections Weighted least connections Random http://www.jscape.com/blog/load-balancing-algorithms http://g33kinfo.com/info/archives/2657

Top K Frequent Elements in Recent X mins

https://www.jiuzhang.com/qa/219/ http://systemdesigns.blogspot.com/2015/12/top-k-requests-during-past-time-interval.html?view=classic

Design TinyURL

Design Twitter

Design Instagram

Design Web Crawler

Resources

Blogs

  • Cherami: Uber Engineering’s Durable and Scalable Task Queue in Go

  • https://redditblog.com/2017/05/24/view-counting-at-reddit/

Website

  • http://www.puncsky.com/blog/2016/02/14/crack-the-system-design-interview/

Video

PreviousTrieNextJargons

Last updated 3 years ago

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