Skip to content

1512. Number of Good Pairs

Difficulty Topics

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

Solution

number-of-good-pairs.py
class Solution:
    def numIdenticalPairs(self, nums: List[int]) -> int:
        n = len(nums)
        res = 0
        for i in range(n):
            for j in range(i+1, n):
                if nums[i] == nums[j]:
                    res += 1

        return res