子集生成

#include<iostream> 
using namespace std;

const int n=5;

void A_print_subset(int n,int *A,int ch){
    for(int i=0;i<ch;i++)   cout<<A[i];
    cout<<" ";
    int s=ch?A[ch-1]+1:1;
    for(int i=s;i<=n;i++){
        A[ch]=i;
        A_print_subset(n,A,ch+1);
    }
    return ;
}
void B_print_subset(int n,int *A,int ch){
    if(ch==n+1){
        for(int i=1;i<=n;i++){
            if(A[i])    cout<<i;
        }
        cout<<" ";
        return ;
    }
    A[ch]=1;    B_print_subset(n,A,ch+1);
    A[ch]=0;    B_print_subset(n,A,ch+1);
}
void C_print_subset(int n){
    for(int i=1;i<(1<<n);i++){
        for(int j=0;j<n;j++){
            if(i&(1<<j))    cout<<j+1;
        }
        cout<<" ";
    }
    return ;
}
int main(){
    int a[n];
    for(int i=0;i<n;i++)    a[i]=i+1;
    A_print_subset(n,a,0);
    cout<<endl;
    B_print_subset(n,a,1);
    cout<<endl;
    C_print_subset(n);
    return 0;
}