Space PROG1163

#include<stdio.h>
int n;
int limit;
void recur(int x){
    char str[n+1];for(int i=0;i<n;i++)str[i] = '0';str[n] = '\0';
    int tx = x;
    int si = n-1;
    while(tx != 0){
        str[si--] = tx%2 + '0';
        tx/=2;
    }
//  printf("Test x : %d, %s\n",x,str);
//  return;
    for(int i=n-1;i>=0;i--){
        if(str[i] == '0'){
            printf("%s ",str);
            str[i] = '1';
            printf("%s\n",str);
            str[i] = '0';
        }
    }
    if(x < limit-2){
        recur(x+1);
    }
}

int main()
{
    scanf("%d",&n);
    limit = 1;
    for(int i=1;i<=n;i++){
        limit *= 2;
    }
    recur(0);
    return 0;
}