1512. Number of Good Pairs-好数对的数目

Given an array of integers nums.

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

Return the number of good pairs.

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 in python:

class Solution:
    def numIdenticalPairs(self, nums: List[int]) -> int:
        c = 0
        for i in range(len(nums)):
            for j in range(i+1, len(nums)):
                if nums[i] == nums[j]:
                    c += 1
        return c