dfs递归枚举

#include<iostream>
using namespace std;

const int N =16;
int state[N];   //0表示未考虑,1表示选择,2表示未选择.
int n;
void dfs(int u){
    if(u>n){
        for(int i=1;i<=n;i++){
            if(state[i] == 1)
                printf("%d ", i);
        }
        cout<<"\n";
        return ;
    }
    state[u] = 2;   //不选择
    dfs(u+1);
    state[u] =0;


    state[u] = 1;   //选择
    dfs(u+1);
    state[u] =0;
}

int main(){
    cin>>n;
    dfs(1);
    return 0;
}