5.找倍数

https://www.acwing.com/problem/content/description/4222/

ab%n=((a%n)b)%n

// a*b%n=((a%n)*b)%n
#include<iostream>
#include<queue>
using namespace std;

typedef pair<string,int> Node;
int n;

int main()
{
    while(cin>>n,n)
    {
        queue<Node> q;
        q.push({"1",1});
        while(q.size()){
            auto t=q.front();
            q.pop();
            if(t.second==0){
                cout<<t.first<<endl;
                break;
            }
            q.push({t.first+"0",t.second*10%n});
            q.push({t.first+"1",(t.second*10+1)%n});
        }
    }
    return 0;
}