求非空子集（定序）

#include<stdio.h>#include<string.h>int n;int a[30];void notempty_subset(int cur){int start = cur?a[cur-1]+1 : 0;for(int i=start; i < n; ++i){a[cur] = i;for(int j = 0; j <= cur; ++j){printf("%d ",a[j]);}putchar(10);notempty_subset(cur+1);}}int main(){//freopen("out.txt","w",stdout);while(scanf("%d", &n) == 1){notempty_subset(0);}}