Find The Multiple---（进制）

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 Given a positive integer n, write a program to find out a nonzero multiple m of n whose decimal representation contains only the digits 0 and 1. You may assume that n is not greater than 200 and there is a corresponding m containing no more than 100 decimal digits.

Input

The input file may contain multiple test cases. Each line contains a value of n (1 <= n <= 200). A line containing a zero terminates the input.

Output

For each value of n in the input print a line containing the corresponding value of m. The decimal representation of m must not contain more than 100 digits. If there are multiple solutions for a given value of n, any one of them is acceptable.

Sample Input

2
6
19
0

Sample Output

10
100100100100100100
111111111111111111

题意：找到一个n的倍数且仅有1和0组成

思路：从1,1开始搜，直到找到倍数为止，有多个答案，输出其中一个即可。dfs

Code：

#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
int n,flag;
void dfs(long long int x,int h)
{
    if(flag||h>19)return ;             ///19之后会出现循环...
    if(x%n==0)
    {
        flag=1;
        printf("%lld\n",x);
    }
    for(int i=0;i<2;i++)
    {
        dfs(x*10+i,h+1);
        if(flag)return ;
    }
}
int main()
{
    while(~scanf("%d",&n)&&n)
    {
        flag=0;
        dfs(1,1);
    }
    return 0;
}