LeetCode 77. Combinations

描述

n个1~n的数，找出含有k个数的组合

解决

回溯

---

class Solution { public: vector<vector<int>> res; vector<int> tmp; vector<vector<int>> combine(int n, int k) { help(res, tmp, n, k, 1, 0); return res; } void help(vector<vector<int>> &res, vector<int> &tmp, int n, int k, int pos, int cnt) { if (cnt == k) { res.push_back(tmp); return ; } for (int i = pos; i <= n; ++i) { tmp.push_back(i); help(res, tmp, n, k, i + 1, cnt + 1); tmp.pop_back(); } return ; } };