Leetcode : 1512. Number of Good Pairs

Problem statement :

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.

Examples :

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

Solution :

  class Solution:
      def numIdenticalPairs(self, nums: List[int]) -> int:
          res =[]
          for i in range(0, len(nums)):
              for j in range(i, len(nums)):
                  if nums[i]==nums[j] and i < j:
                      res.append([nums[i],nums[j]])
          return len(res)
        

Explanation :