leetcode77-组合

77. 组合

class Solution {
public:
    vector<vector<int>> res;
    vector<int> path;
    void backTracking(int n,int k,int startIndex)
    {
        if(path.size()==k)
        {
            res.push_back(path);return;
        }
        //for(int i=startIndex;i<=n;i++)
        for(int i=startIndex;i<=n-(k-path.size())+1;i++)
        {
            path.push_back(i);
            backTracking(n,k,i+1);
            path.pop_back();
        }
    }
    vector<vector<int>> combine(int n, int k) {
        backTracking(n,k,1);
        return res;
    }
};