Description

Submission

class Solution {
    int comb2(int n) {
        return n * (n - 1) / 2;
    }
public:
    int numIdenticalPairs(vector<int>& nums) {
        map<int, int> cnt;

        for(int x: nums) {
            cnt[x]++;
        }

        map<int, int> occur;
        int ret = 0;
        for(auto p: cnt) {
           ret += comb2(p.second);
        }

        return ret;
    }
};