1512. Number of Good Pairs

https://leetcode.com/problems/number-of-good-pairs

Description

Given an array of integers nums, return the number of good pairs.

A pair (i, j) is called good if nums[i] == nums[j] and i < j.

Example 1:

**Input:** nums = [1,2,3,1,1,3]
**Output:** 4
**Explanation:** There are 4 good pairs (0,3), (0,4), (3,4), (2,5) 0-indexed.

Example 2:

**Input:** nums = [1,1,1,1]
**Output:** 6
**Explanation:** Each pair in the array are *good*.

Example 3:

**Input:** nums = [1,2,3]
**Output:** 0

Constraints:

• 1 <= nums.length <= 100

• 1 <= nums[i] <= 100

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