532

class Solution {
public:
    int findPairs(vector<int>& nums, int k) {
        unordered_map<int, int> count;
        for(int x: nums) count[x]++;

        int ans = 0;
        for(auto x: count)
            if((k>0 && count.count(x.first+k)) || (k == 0  && x.second > 1))
                ans++;

        return ans;
    }
};