1 /*
 2     Name: hdu--1372--Knight Moves
 3     Copyright: ?2017 日天大帝
 4     Author: 日天大帝 
 5     Date: 30/04/17 20:31
 6     Description: bfs
 7 */
 8 #include<iostream>
 9 #include<queue> 
10 #include<cstring>
11 #include<string>
12 using namespace std;
13 int bfs();
14 struct node{
15     int x,y,ct;
16 }s,e;
17 queue<node> q;
18 int vis[10][10];
19 int ans;
20 int dir[8][2]={-2,1, -1,2, 1,2, 2,1, 2,-1, 1,-2, -1,-2, -2,-1};
21 int main(){
22     ios::sync_with_stdio(false);
23     
24     string str1,str2;
25     while(cin>>str1>>str2){
26         s.x = str1.at(0) - ‘a‘;
27         s.y = str1.at(1) - 48-1;
28         e.x = str2.at(0) - ‘a‘;
29         e.y = str2.at(1) - 48-1;
30         ans = 0;
31         memset(vis,0,sizeof(vis));
32         cout<<"To get from "<<str1<<" to "<<str2<<" takes "<<bfs()<<" knight moves."<<endl;
33     }
34     return 0;
35 }
36 int bfs(){
37     while(!q.empty())q.pop();
38     s.ct = 0;
39     vis[s.x][s.y] = 1;
40     q.push(s);
41     node a,temp;
42     while(!q.empty()){
43         temp = q.front();q.pop();
44         if(temp.x == e.x && temp.y == e.y){
45             return temp.ct;
46         }
47         for(int i=0; i<8; ++i){
48             a = temp;
49             a.x += dir[i][0];
50             a.y += dir[i][1];
51             if(a.x<0 || a.y<0 || a.x >=8 || a.y >= 8 || vis[a.x][a.y])continue;
52             vis[a.x][a.y] = 1;
53             a.ct++;
54             q.push(a);
55         }
56     }
57     return -1;
58 }