poj 3126 bfs

不知道为什么，二种方法一样，第一种就是wrong,第二种就AC了

#include <stdio.h>
#include <iostream>
#include <queue>
#include <cmath>
using namespace std;
int p[9999]={0},visited[9999]={0};
bool isprime(int n){
    for(int i=2;i<(int)sqrt((double)n);i++){
          if(n%i==0)
             return 0;
    }
     return 1;
}
int bfs(int s,int e){
    if(s==e)
        return 0;
    queue<int> q;
    q.push(s);
    p[s]=0;
    visited[s]=1;
    while(!q.empty()){
       int temp=q.front();
       q.pop();
       for(int i=0;i<10;i++){
            int y1=(temp/10)*10+i;
            if(isprime(y1)&&!visited[y1]){
                p[y1]=p[temp]+1;
                q.push(y1);
                visited[y1]=1;                              
            } 
             int y2=(temp/100)*100+i*10+temp%10;
            if(isprime(y2)&&!visited[y2]){
                p[y2]=p[temp]+1;
                q.push(y2);
                visited[y2]=1;                              
            }        
             int y3=(temp/1000)*1000+i*100+temp%100;
            if(isprime(y3)&&!visited[y3]){
                p[y3]=p[temp]+1;
                q.push(y3);
                visited[y3]=1;                              
            } 
            if(i){       
              int y4=temp%1000+i*1000;
              if(isprime(y4)&&!visited[y4]){
                p[y4]=p[temp]+1;
                q.push(y4);
                visited[y4]=1;                              
              }               
            }
       if(visited[e])
          return p[e];    
       }    
                   
    }
    return 0; 
}
int main(){
    int n,s,e;
    cin>>n;
    while(n--){
       cin>>s>>e;
       memset(visited,0,sizeof(visited));
       memset(p,0,sizeof(p));
       int t=bfs(s,e);
       cout<<t<<endl;           
    }
    system("PAUSE");
    return 0;
}

-----------------------------------------------------------------------------------------------

#include <iostream>
#include <queue>
#include <math.h>
using namespace std;
int a, b;
int p[9999] = { 0 };
int visited[9999] = { 0 };
bool isprime(int x) {

    for (int i = 2; i <= sqrt((double) x); ++i) {
        if (x % i == 0)
            return false;
    }
    return true;
}
int BFS(int s, int r) {
    queue<int> q;
    q.push(s);
    p[s] = 0;
    visited[s] = 1;
    while (!q.empty()) {
        int temp = q.front();
       q.pop();
       for (int i = 0; i <= 9; i++) {
            int y1 = (temp / 10) * 10 + i;
            if (isprime(y1) && !visited[y1]) {
                q.push(y1);
                p[y1] = p[temp] + 1;
                visited[y1] = 1;
            }
            int y2 = temp % 10 + (temp / 100) * 100 + i * 10;
           if (isprime(y2) && !visited[y2]) {
                q.push(y2);
                p[y2] = p[temp] + 1;
                visited[y2] = 1;
            }
            int y3 = temp % 100 + (temp / 1000) * 1000 + 100 * i;
            if (isprime(y3) && !visited[y3]) {
                q.push(y3);
                p[y3] = p[temp] + 1;
                visited[y3] = 1;
            }
            if (i != 0) {
                int y4 = temp % 1000 + i * 1000;
                if (isprime(y4) && !visited[y4]) {
                    q.push(y4);
                    p[y4] = p[temp] + 1;
                    visited[y4] = 1;
                }
            }
            if (visited[r])
               return p[r];
        }
    }
    return 0;
}
int main() {
    int n;
    cin >> n;
    while (n--) {
        memset(visited,0,sizeof(visited));
        memset(p,0,sizeof(p));
        cin >> a >> b;
        cout << BFS(a, b) << endl;

    }
    return 0;
}