思路：

和几天前集训的题一模一样。
上次打深搜，这次打广搜

$code$

#include<iostream>
#include<cstdio>
#include<queue>

using namespace std;

int n;
queue<pair<int, string> > q;
bool v[1000010];

int main() {
    
	scanf("%d", &n);
	q.push(make_pair(1, "1"));
	v[1] = 1;
	while(!q.empty()) {
    
		int r = q.front().first;
		string ss = q.front().second;
		q.pop();
		int g = r * 10 % n;
		if(!v[g]) {
    
			v[g] = 1;
			q.push(make_pair(g, ss + "0"));
			if(g == 0) {
    
				cout<<ss + "0";
				return 0;
			}
		}
		g = (r * 10 + 1) % n;
		if(!v[g]) {
    
			v[g] = 1;
			q.push(make_pair(g, ss + "1"));
			if(g == 0) {
    
				cout<<ss + "1";
				return 0;
			}
		}
	}
	cout<<-1;
	return 0;
}