数组中n,k 的输出

//
// Created by dongfucai on 2019/1/1.
//

#include <vector>
#include <iostream>

using namespace std;

//If n = 4 and k = 2, a solution is:
//[
//[2,4],
//[3,4],
//[2,3],
//[1,2],
//[1,3],
//[1,4],
//]

class Solution {

public:
    void solution (int n, int k) {

        if (n < k) {
            return;
        }
        vector<vector<int> > res;
        vector<int> temp;
        int pos = 1;
        dfs(k, n, pos, temp, res);

    }
    void dfs(int &k, int &n, int pos, vector<int> temp, vector<vector<int> > &res) {
        if (temp.size() == k) {
            for (int i = 0; i < k; ++i) {
                cout << temp[i] << " ";
            }
            cout << endl;
            res.push_back(temp);
            return;
        }
        for (int i = pos; i <= n; ++i) { // 选择基本是都是for 或者 if
            temp.push_back(i);
            dfs(k, n, i + 1, temp, res);  // 这个pos位置要注意一下啊，pos + 1 ,还是 i + 1  有条件的选择
            temp.pop_back();
        }
    }
};

int main() {

    Solution  s;
    s.solution(4, 2);
}