[kuangbin带你飞]专题一 简单搜索 - F - Prime Path 

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<algorithm>
 5 #include<queue>
 6 using namespace std;
 7 struct node
 8 {
 9     int x;
10     int s;
11 };
12 bool prim[10005];
13 bool vis[10005];
14 int chr(int x,int i,int j)
15 {
16     int b,s = 1;
17     int tmp = 0;
18     for(int z = 1; z<= 4; z++)
19     {
20         b = x%10;
21         x/=10;
22         if(i==z)    b = j;
23         tmp+=s*b;
24         s*=10;
25     }
26     return tmp;
27 }
28 int main()
29 {
30 //    freopen("in.in","r",stdin);
31     for(int i = 2; i <= 10000; i++)
32     {
33         if(prim[i])    continue;
34         for(int j = 2; j <= 10000/i; j++)
35             prim[i*j] = true;
36     }
37     queue<node>q;
38     node s, t;
39     int n, a, b, tmp;
40     bool flag;
41     scanf("%d",&n);
42     while(n--)
43     {
44         flag = false;
45         memset(vis,false,sizeof(vis));
46         scanf("%d%d",&a,&b);
47         s.x = a;
48         s.s = 0;
49         q.push(s);
50         while(q.size())
51         {
52             s = q.front();
53             q.pop();
54             t.s = s.s + 1;
55             vis[s.x] = true;
56             if(s.x == b)
57             {
58                 flag = true;
59                 break;
60             }
61             for(int i = 1; i <= 4; i++)
62                 for(int j = 0; j <= 9; j++)
63                 {
64                     if(i==4 && j==0)    continue;
65                     t.x = chr(s.x,i,j);
66                     if(prim[t.x] || vis[t.x])    continue;
67                     q.push(t);
68                 }
69         }
70         while(q.size())    q.pop();
71         if(flag)    cout<<s.s<<endl;
72         else        cout<<"Impossible"<<endl;
73     }
74     return 0;
75 }

 

posted @ 2015-01-28 15:25  天I火  阅读(248)  评论(0)  编辑  收藏  举报