UVa 439骑士的移动（BFS）

https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=380

做了这道题之后对BFS总算是有了点认识了。

 #include<iostream>
 #include<cstring>
 using namespace std;

 int map[][];
 typedef struct node
 {
     int x, y, z;
     node(int a, int b, int c)  { x = a; y = b; z = c; }
     node() {}
 }queue;

 queue q[];

 int d[][] = { { ,  }, { , - }, { -, - }, { -,  }, { ,  }, { , - }, { -,  }, { -, - } };
 int bfs(int x1, int y1, int x2, int y2)
 {
     int move = , number = ;
     if (x1 == x2 && y1 == y2)  return ;
     memset(map, , sizeof(map));
     q[] = node(x1, y1, );
     while (move < number)
     {
         queue p = q[move++];
         for (int k = ; k < ; k++)
         {
             int xx = p.x + d[k][];
             int yy= p.y + d[k][];
             if (xx == x2 && yy == y2)  return p.z + ;
             if (!map[xx][yy] && xx> && xx< && yy> && yy < )
             {
                 map[xx][yy] = ;
                 q[number++] = node(xx, yy, p.z + );
             }
         }
     }
 }

 int main()
 {
     char s1, s2;
     int x1, x2, y1, y2;
     while (cin >> s1 >> y1 >> s2 >> y2)
     {
         x1 = (int)(s1 - 'a' + );
         x2 = (int)(s2 - 'a' + );
         int x=bfs(x1, y1, x2, y2);
         cout << "To get from "<<s1<<y1<< " to " <<s2<<y2<< " takes "<<x <<" knight moves."<< endl;
     }
     return ;
 }