leetcode

0 class Solution {

1 public:

2 vector<vector<int>> combinationSum3(int k, int n) {

3 vector<vector<int>> res;

4 vector<int> comb;

5 for (uint16_t i = 0; i < (1 << 9); i++) {

6 if (__builtin_popcount(i) != k) continue;

7 int crnt = i, total = 0;

8

9 comb.clear();

10 while (crnt) {

11 comb.push_back(__builtin_ffs(crnt));

12 total += comb.back();

13 crnt &= crnt - 1;

14 }

15 if (total == n) res.push_back(comb);

16 }

17 return res;

18 }

19 };