92. Recursive implementation of exponential enumeration

#include<iostream>
using namespace std;

int n;
//u Indicates the current number of bits to enumerate ,state Represents the status of everyone , Use state compression ,32 position int Enough to compress all States 
void dfs(int u,int state){
    if(u == n){// Be careful , Is to n When you push the loop , No n-1, Because of n-1 Indicates current needs   Enumerate the n position 
        for(int i = 0;i < n;i++)
            if(state >> i & 1) cout << i + 1 << ' ';
        cout << endl;
        return; //return Don't forget .
    }
    dfs(u + 1,state);
    dfs(u + 1,state | 1 << u);
}

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