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
dfs 枚举 cur×10和和cur×10+1 即可，long 最长的长度是 19，所以如果位数大于 19 就直接 return 了
import java.util.Scanner;
public class Main {
static int n;
static boolean flag;
static void dfs(int idx,long cur) {
if(idx > 19 || flag)
return;
if(cur % n == 0) {
flag = true;
System.out.println(cur);
return;
}
dfs(idx + 1,cur * 10);
dfs(idx + 1,cur * 10 + 1);
}
public static void main(String[] args) {
Scanner cin = new Scanner(System.in);
while(cin.hasNext()) {
n = cin.nextInt();
if(n == 0)
break;
flag = false;
dfs(1,1L);
}
}
}
