CH0301 递归实现指数型枚举

#include<iostream>
#include<cstring>
#include<vector>
#include<algorithm>
using namespace std;
const int maxn = 1000 + 10;
const int inf = 0x7fffffff;
vector<int>chose;
int n;
void calc(int x){

    if (x == n + 1){  //问题边界
        for (int i = 0; i < chose.size(); i++)
            printf("%d ",chose[i]);
        cout << endl;
        return;
    }
    //"不选x"的分支
    calc(x + 1);  //子问题
    //"选x"的分支
    chose.push_back(x);  //记录x已被选择
    calc(x + 1);  //子问题
    chose.pop_back();    //准备回溯到上一问题之前，还原现场
}
int main()
{
    cin >> n;
    calc(1);
    
    return 0;
}