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