搜索-H

• 原题

  Description
  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

• 思路解析
  寻找能整除N的，由0,1组成的数。

• AC代码

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
bool vis;
int n;
void dfs(unsigned __int64 x,int n,int k){
    if(vis) return;
    if(x%n==0){
        printf("%I64u\n",x);
        vis=true;
        return;
    }
    if(k==19) return;
    dfs(x*10,n,k+1);
    dfs(x*10+1,n,k+1);
}
int main(){
    while(scanf("%d",&n)){
        if(n==0) break;
        vis=false;
        dfs(1,n,0);
    }
    return 0;
}