Untitled

class Solution {
public:
    vector<vector<int>> combine(int n, int k) {
        int i=0;
        vector<int>p(k,0);
        vector<vector<int>> res;
        while(i>=0){
            p[i]++;
            if(p[i]>n) --i;
            else if(i==k-1) res.push_back(p);
            else{
                i++;
                p[i]=p[i-1];
            }
        }
        return res;
        
    }
};


/* 
class Solution {
public:
    void solve(int k,int start,vector<int>&comb,vector<vector<int>>&res,int n){
        if(comb.size()==k) {
            res.push_back(comb);
            return;
        }
        for(int i=start;i<=n;i++){
            comb.push_back(i);
            solve(k,i+1,comb,res,n);
            comb.pop_back();
        }
    }

    vector<vector<int>> combine(int n, int k) {
        vector<vector<int>> res;
        vector<int> comb;
        solve(k,1,comb,res,n);
        return res;
    }
}; */