HDU 1372 Knight Moves【BFS】

 1 #include<iostream>  
 2 #include<cstdio>  
 3 #include<cstring>  
 4 #include<algorithm>  
 5 #include<queue>
 6 #define maxn 105
 7 using namespace std;
 8 struct node
 9 {
10     int x,y;
11     int step;    
12 } now,next,st,en;
13 queue<node>q;
14 char m,n;
15 int vis[maxn][maxn];
16 int dir[8][2]={{2,1},{1,2},{-1,2},{-2,1},{-2,-1},{-1,-2},{1,-2},{2,-1}};
17 void bfs(int x,int y)
18 {
19     now.x=x;now.y=y;now.step=0;
20     while(!q.empty()) q.pop();
21     q.push(now);
22     vis[x][y]=1;
23     while(!q.empty())
24     {
25         now=q.front();q.pop();
26         if(now.x==en.x&&now.y==en.y)
27         {
28             printf("To get from %c%d to %c%d takes %d knight moves.\n",m,st.y,n,en.y,now.step);
29             return;
30         };
31         for(int i=0;i<8;i++)
32         {
33             next.x=now.x+dir[i][0];
34             next.y=now.y+dir[i][1];
35             if(next.x<1||next.y>8||next.y<1||next.y>8) continue;
36             if(!vis[next.x][next.y])
37             {
38                 vis[next.x][next.y]=1;
39                 next.step=now.step+1;
40                 q.push(next);
41                 if(next.x==en.x&&next.y==en.y)
42                 {
43                     printf("To get from %c%d to %c%d takes %d knight moves.\n",m,st.y,n,en.y,next.step);
44                     return;                    
45                 }
46             }
47         }
48     }    
49 }
50 int main()
51 {
52     while(cin>>m>>st.y>>n>>en.y)
53     {
54         memset(vis,0,sizeof(vis));
55         st.x=m-‘a‘+1;
56         en.x=n-‘a‘+1;
57         bfs(st.x,st.y);
58     }
59 }