UVa 439骑士的移动（BFS）

Posted 2020-08-23 谦谦君子，陌上其华

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。

 1 #include<iostream>
 2 #include<cstring>
 3 using namespace std;
 4 
 5 int map[10][10];
 6 typedef struct node
 7 {
 8     int x, y, z;
 9     node(int a, int b, int c)  { x = a; y = b; z = c; }
10     node() {}
11 }queue;
12 
13 queue q[100];
14 
15 int d[8][2] = { { 2, 1 }, { 2, -1 }, { -2, -1 }, { -2, 1 }, { 1, 2 }, { 1, -2 }, { -1, 2 }, { -1, -2 } };
16 int bfs(int x1, int y1, int x2, int y2)
17 {
18     int move = 0, number = 1;
19     if (x1 == x2 && y1 == y2)  return 0;
20     memset(map, 0, sizeof(map));
21     q[0] = node(x1, y1, 0);
22     while (move < number)
23     {
24         queue p = q[move++];
25         for (int k = 0; k < 8; k++)
26         {
27             int xx = p.x + d[k][0];
28             int yy= p.y + d[k][1];
29             if (xx == x2 && yy == y2)  return p.z + 1;
30             if (!map[xx][yy] && xx>0 && xx<9 && yy>0 && yy < 9)
31             {
32                 map[xx][yy] = 1;
33                 q[number++] = node(xx, yy, p.z + 1);
34             }
35         }
36     }
37 }
38 
39 int main()
40 {
41     char s1, s2;
42     int x1, x2, y1, y2;
43     while (cin >> s1 >> y1 >> s2 >> y2)
44     {
45         x1 = (int)(s1 - ‘a‘ + 1);
46         x2 = (int)(s2 - ‘a‘ + 1);
47         int x=bfs(x1, y1, x2, y2);
48         cout << "To get from "<<s1<<y1<< " to " <<s2<<y2<< " takes "<<x <<" knight moves."<< endl;
49     }
50     return 0;
51 }