hdu 1285 确定比赛名次 （topsort）

 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 
14 const int my_max_N = 505;
15 int my_indeg[my_max_N], n, m, a, b;
16 vector <int> my_G[my_max_N];
17 
18 void topsort()
19 {
20     queue <int> Q, ans;
21 
22     while (1)
23     {
24         for (int i = 1; i <= n; ++ i)
25             if (my_indeg[i] == 0)
26             {
27                 Q.push(i), ans.push(i);
28                 my_indeg[i] = -1;
29                 break;
30             }
31 
32         if (Q.empty()) break;
33         while (!Q.empty())
34         {
35             int my_now = Q.front();
36             for (int i = 0; i < my_G[my_now].size(); ++ i)
37                 -- my_indeg[my_G[my_now][i]];
38             my_G[my_now].clear();
39             Q.pop();
40         }
41     }
42 
43     /**
44         Answer Output
45     */
46     printf("%d", ans.front());
47     ans.pop();
48     while (!ans.empty())
49     {
50         printf(" %d", ans.front());
51         ans.pop();
52     }
53     printf("\n");
54 }
55 
56 int main()
57 {
58     while (~scanf("%d%d", &n, &m))
59     {
60         memset(my_indeg, 0, sizeof (my_indeg));
61 
62         while (m --)
63         {
64             scanf("%d%d", &a, &b);
65             my_G[a].push_back(b);
66             ++ my_indeg[b];
67         }
68 
69         topsort();
70     }
71     return 0;
72 }