POJ1426Find The Multiple[BFS]

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <queue>
using namespace std;
const int N=1e6,INF=1e9;
typedef long long ll;
ll n;
queue<ll>q;
ll bfs(){
    ll x;
    while(!q.empty()) q.pop();
    q.push(1);
    while(!q.empty()){
        x=q.front();
        q.pop();
        if(x%n==0) return x;
        q.push(x*10);
        q.push(x*10+1);
    }
}
int main(){
    while(~scanf("%lld",&n)){
        if(n==0) break;
        printf("%lld\n",bfs());
    }
    return 0;
}