poj---3126---Prime Path

题目链接：http://poj.org/problem?id=3126

#include <cstdio>
#include <cstring>
#include <iostream>
#include <cmath>
#include<vector>
#include<queue>
#include<algorithm>

using namespace std;
typedef long long LL;

const int maxn=500009;
const int INF=0x3f3f3f3f;
const int mod=2009;
int a, b;
int cnt[maxn], vis[maxn];

bool Isprime(int m)
{
    int k=sqrt(m);
    for(int i=2; i<=k; i++)
    {
        if(m%i==0)
            return false;
    }
    return true;
}
int bfs()
{
    queue<int >Q;
    cnt[a]=0;
    vis[a]=1;
    Q.push(a);

    while(Q.size())
    {
        int t=Q.front();
        Q.pop();

        for(int i=0; i<=9; i++)
        {
            int t1=t/10*10+i;
            if(Isprime(t1)&&!vis[t1])
            {
                cnt[t1]=cnt[t]+1;
                vis[t1]=1;
                Q.push(t1);
            }

            int t2=t/100*100+i*10+t%10;
            if(Isprime(t2)&&!vis[t2])
            {
                cnt[t2]=cnt[t]+1;
                vis[t2]=1;
                Q.push(t2);
            }

            int t3=t/1000*1000+i*100+t%100;
            if(Isprime(t3)&&!vis[t3])
            {
                cnt[t3]=cnt[t]+1;
                vis[t3]=1;
                Q.push(t3);
            }

            if(i)
            {
                int t4=i*1000+t%1000;
                if(Isprime(t4)&&!vis[t4])
                {
                    cnt[t4]=cnt[t]+1;
                    vis[t4]=1;
                    Q.push(t4);
                }
            }

            if(vis[b])
                return cnt[b];
        }
    }
    return 0;
}
int main()
{
    int  T;
    scanf("%d", &T);

    while(T--)
    {
        memset(cnt, 0, sizeof(cnt));
        memset(vis, 0, sizeof(vis));
        scanf("%d %d", &a, &b);
        int ans=bfs();
        printf("%d
", ans);
    }
    return 0;
}