51nod 1109 01组成的n的倍数（同余定理）

记录一下新学的骚操作

#include<bits/stdc++.h>
#define LL long long
#define Max 100005
#define Mod 1e9+7
const LL mod=1e9+7;
const LL inf=0x3f3f3f3f;
using namespace std;
struct node
{
    string ans;
    int num;
};
int n;
queue<node>q;
int vis[2000005];
node now,next;
void bfs(){

   // printf("11111\n");
    now.ans="10";
    now.num=10%n;
    vis[now.num]=1;
    q.push(now);
    now.ans="11";
    now.num=11%n;
    vis[now.num]=1;
    q.push(now);
    while(q.size()){
        now=q.front();
        q.pop();
        if(now.num==0){
            cout<<now.ans<<endl;
            return ;
        }
        for(int i=0;i<=1;i++){
            if(i==0)
                next.ans=now.ans+"0";
            else
               next.ans=now.ans+"1";
            next.num=(now.num*10+i)%n;
            if(vis[next.num])
                continue;
            vis[next.num]=1;
            q.push(next);
        }
    }
}
int main()
{
    scanf("%d",&n);
    if(n==1)
        printf("1\n");
    else
        bfs();
    return 0;
}