[LeetCode] Combinations

class Solution {public:    vector<vector<int> > ret;    vector<int> sln;        void DFS(int n, int k, int m) {        if (k == 0) {            ret.push_back(sln);            return;        }                if (m > n) return;                DFS(n, k, m + 1);                sln.push_back(m);        DFS(n, k - 1, m + 1);        sln.pop_back();    }        vector<vector<int> > combine(int n, int k) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        ret.clear();                DFS(n, k, 1);                return ret;    }};

Small Case: 4ms

Large Case: 52ms