K-diff Pairs in an Array.cpp

// Runtime: 44 ms (Top 28.49%) | Memory: 13.2 MB (Top 57.38%)
class Solution {
public:
    int findPairs(vector<int>& nums, int k) {
        unordered_map<int,int> a;
        for(int i:nums)
            a[i]++;
        int ans=0;
        for(auto x:a)
        {
            if(k==0)
            {
                if(x.second>1)
                ans++;
            }
             else if(a.find(x.first+k)!=a.end())
                ans++;
        }

        return ans;
    }
};