POJ 1426, Find The Multiple

Time Limit: 1000MS  Memory Limit: 10000K
Total Submissions: 4446  Accepted: 1908  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
2
6
19
0

Sample Output
10
100100100100100100
111111111111111111

Source
Dhaka 2002

---

// POJ1426.cpp : Defines the entry point for the console application.
//

#include <iostream>
using namespace std;

int main(int argc, char* argv[])
{
    int N;
    unsigned long long que[800000];

    while (cin >> N && N != 0)
    {
        int front = 0, rear = 0;
        que[rear++] = 1;

        unsigned long long num;
        while(front != rear)
        {
            num = que[front++];
            front %= 800000;

            if ((num % N) == 0) 
                break;

            num *= 10;
            que[rear++] = num;
            rear %= 800000;

            ++num;
            que[rear++] = num;
            rear %= 800000;
        }
        cout << num << endl;
    }
    return 0;
}