0918. Maximum Sum Circular Subarray

https://leetcode.com/problems/maximum-sum-circular-subarray

Description

Given a circular integer array nums of length n, return the maximum possible sum of a non-empty subarray of nums.

A circular array means the end of the array connects to the beginning of the array. Formally, the next element of nums[i] is nums[(i + 1) % n] and the previous element of nums[i] is nums[(i - 1 + n) % n].

A subarray may only include each element of the fixed buffer nums at most once. Formally, for a subarray nums[i], nums[i + 1], ..., nums[j], there does not exist i <= k1, k2 <= j with k1 % n == k2 % n.

Example 1:

**Input:** nums = [1,-2,3,-2]
**Output:** 3
**Explanation:** Subarray [3] has maximum sum 3

Example 2:

**Input:** nums = [5,-3,5]
**Output:** 10
**Explanation:** Subarray [5,5] has maximum sum 5 + 5 = 10

Example 3:

**Input:** nums = [3,-1,2,-1]
**Output:** 4
**Explanation:** Subarray [2,-1,3] has maximum sum 2 + (-1) + 3 = 4

Example 4:

**Input:** nums = [3,-2,2,-3]
**Output:** 3
**Explanation:** Subarray [3] and [3,-2,2] both have maximum sum 3

Example 5:

**Input:** nums = [-2,-3,-1]
**Output:** -1
**Explanation:** Subarray [-1] has maximum sum -1

Constraints:

• n == nums.length

• 1 <= n <= 3 * 104

• -3 * 104 <= nums[i] <= 3 * 104

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