POJ 1426 BFS-Find The Multiple

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.

题意：

给你一个正整数n，寻找一个只由0和1组成的n的倍数。

题解：

深度优先搜索问题，从各位开始搜索每一位为0和1的所有可能

即搜索：

0 1

10 11

100 101 110 111

…..

按位进行深度优先搜索即可。

#include <iostream>
#include <queue>
typedef unsigned long long uLL;
using namespace std;

queue<uLL> q;
uLL n;
uLL m;

void bfs()
{
while(!q.empty()) q.pop();
q.push(1);
while(!q.empty())
{
m = q.front();
q.pop();
if(m % n == 0)
return;
m = m * 10;
q.push(m);
m = m + 1;
q.push(m);
}
}

int main()
{
while(cin >> n && n)
{
bfs();
cout << m << endl;
}
return 0;
}