HDU 1010 深搜+奇偶剪枝

 1 #include<cstdio>
 2 #include<cstdlib>
 3 using namespace std;
 4 char maze[10][10];
 5 int dx[4] = { -1, 1, 0, 0 };
 6 int dy[4] = { 0, 0, -1, 1 };
 7 int sx, sy, ex, ey;
 8 bool escape;
 9 void dfs(int t, int x, int y)
10 {
11     if (maze[x][y] == ‘D‘&&t == 0 || escape)
12     {
13         escape = true; return;
14     }
15     char tmp = maze[x][y];
16     maze[x][y] = ‘X‘;
17     int T = t - abs(ex - x) - abs(ey - y);
18     if (T >= 0 && T % 2 == 0)
19     {
20         for (int i = 0; i < 4; i++)
21         {
22             int r = dx[i] + x, c = dy[i] + y;
23             if (maze[r][c] == ‘.‘ || maze[r][c] == ‘D‘)
24                 dfs(t - 1, r, c);
25         }
26     }
27     maze[x][y] = tmp;
28 }
29 int main()
30 {
31     int n, m, t;
32     while (scanf("%d%d%d", &n, &m, &t) && n)
33     {
34         for (int i = 1; i <= n; i++)
35             scanf("%s", maze[i]+1);
36         for (int i = 1; i <= n; i++)
37         {
38             for (int j = 1; j <= m; j++)
39             {
40                 if (maze[i][j] == ‘S‘)
41                     sx = i, sy = j;
42                 if (maze[i][j] == ‘D‘)
43                     ex = i, ey = j;
44             }
45         }
46         escape = false;
47         dfs(t, sx, sy);
48         printf(escape ? "YES\n" : "NO\n");
49     }
50     return 0;
51 }