【leetCode刷题日记】 77. Combinations

class Solution {private:    vector<vector<int>> res;    void generateCombinations(int n,int k,int start,vector<int>& p){        if(p.size() == k){            res.push_back(p);            return;        }        for(int i=start;i<=n;i++){            p.push_back(i);            generateCombinations(n, k, i+1, p);            p.pop_back();        }        return;    }public:    vector<vector<int>> combine(int n, int k) {        vector<int>p;        generateCombinations(n, k, 1, p);        return res;    }};