2354. Number of Excellent Pairs

class Solution:
    def countExcellentPairs(self, nums: List[int], k: int) -> int:
        s = set(nums)
        ans = 0
        cnt = Counter()
        for v in s:
            cnt[v.bit_count()] += 1
        for v in s:
            t = v.bit_count()
            for i, x in cnt.items():
                if t + i >= k:
                    ans += x
        return ans

class Solution {
    public long countExcellentPairs(int[] nums, int k) {
        Set<Integer> s = new HashSet<>();
        for (int v : nums) {
            s.add(v);
        }
        long ans = 0;
        int[] cnt = new int[32];
        for (int v : s) {
            int t = Integer.bitCount(v);
            ++cnt[t];
        }
        for (int v : s) {
            int t = Integer.bitCount(v);
            for (int i = 0; i < 32; ++i) {
                if (t + i >= k) {
                    ans += cnt[i];
                }
            }
        }
        return ans;
    }
}

class Solution {
public:
    long long countExcellentPairs(vector<int>& nums, int k) {
        unordered_set<int> s(nums.begin(), nums.end());
        vector<int> cnt(32);
        for (int v : s) ++cnt[__builtin_popcount(v)];
        long long ans = 0;
        for (int v : s) {
            int t = __builtin_popcount(v);
            for (int i = 0; i < 32; ++i) {
                if (t + i >= k) {
                    ans += cnt[i];
                }
            }
        }
        return ans;
    }
};

func countExcellentPairs(nums []int, k int) int64 {
	s := map[int]bool{}
	for _, v := range nums {
		s[v] = true
	}
	cnt := make([]int, 32)
	for v := range s {
		t := bits.OnesCount(uint(v))
		cnt[t]++
	}
	ans := 0
	for v := range s {
		t := bits.OnesCount(uint(v))
		for i, x := range cnt {
			if t+i >= k {
				ans += x
			}
		}
	}
	return int64(ans)
}