poj 3041 Asteroids (最小点覆盖)

 1 #include <map>
 2 #include <queue>
 3 #include <cmath>
 4 #include <vector>
 5 #include <string>
 6 #include <cstdio>
 7 #include <cstring>
 8 #include <climits>
 9 #include <iostream>
10 #include <algorithm>
11 #define INF 0xffffff
12 using namespace std;
13 const int my_max = 505;
14 
15 int n, k, a, b, my_ans, my_line[my_max][my_max], my_book[my_max], my_right[my_max];
16 
17 bool my_dfs(int x)
18 {
19     for (int i = 1; i <= n; ++ i)
20     {
21         if (!my_book[i] && my_line[x][i])
22         {
23             my_book[i] = 1;
24             if (!my_right[i] || my_dfs(my_right[i]))
25             {
26                 my_right[i] = x;
27                 return true;
28             }
29         }
30     }
31     return false;
32 }
33 
34 int main()
35 {
36     while (~scanf("%d%d", &n, &k))
37     {
38         my_ans = 0;
39         memset(my_line, 0, sizeof(my_line));
40         memset(my_right, 0, sizeof(my_right));
41 
42         while (k --)
43         {
44             scanf("%d%d", &a, &b);
45             my_line[a][b] = 1;
46         }
47         for (int i = 1; i <= n; ++ i)
48         {
49             memset(my_book, 0, sizeof(my_book));
50             if (my_dfs(i)) my_ans ++;
51         }
52 
53         printf("%d\n", my_ans);
54     }
55     return 0;
56 }