搜索练习13/poj/problem1426 Find The Multiple/bfs

http://poj.org/problem?id=1426

Find The Multiple

Time Limit: 1000MS Memory Limit: 10000KTotal Submissions: 30986 Accepted: 12886 Special Judge

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

26190

Sample Output

10100100100100100100111111111111111111

题意：给出一个数n，然后求得一个数字k，数字满足：能被n整除，每一位只有0,1。这样的数字k会有很多个，然以输出一个就可以。

思路：n的最大值为200，用dfs从数字k的个位开始往高位搜索，每一位只有0或1。找到能被n整除的时候输出就可以了。最大是19位，long long 刚好。

AC代码：

#include<cstdio>#define LL long longLL n;int flag;void dfs(LL num){    if(num%n==0)    {        flag=1;        printf("%lld\n",num);        return ;    }    if(num>=1e18)        return ;    dfs(num*10);    if(flag)        return ;    dfs(num*10+1);        return ;}int main(){    while(~scanf("%lld",&n))    {        if(n==0)            break;        flag=0;        dfs(1);    }}