# Leetcode 1512. Number of Good Pairs

## 題解

### 哈希表

class Solution:
    def numIdenticalPairs(self, nums: List[int]) -> int:
        count = {}
        for num in nums:
            if num not in count:
                count[num] = 1
            else:
                count[num] += 1
        output = 0
        for key in count:
            c = count[key]
            if c > 1:
                output += c * (c - 1) // 2
        return output