HDU 1285 确定比赛名次

拓扑排序模板题，判断当前点出度与入度。
 1 #include<cstdio>
 2 #include<cstring>
 3 #include<cstdlib>
 4 
 5 struct N
 6 {
 7     int data;
 8     int n;
 9     struct N *next;
10 }*head[510];
11 
12 void init(int n)
13 {
14     for(int i = 1;i <= n; i++)
15     {
16         head[i] = (struct N *)malloc(sizeof(struct N));
17         head[i]->next = NULL;
18         head[i]->n = 0;
19         head[i]->data = -1;
20     }
21 }
22 
23 int link(int u,int v)
24 {
25     struct N *p1,*p2;
26     for(p1 = head[u],p2 = p1->next; p2 != NULL; p1 = p1->next,p2 = p2->next)
27     {
28         if(v == p2->data) return 0;
29         if(p1->data < v && p2->data > v)
30         {
31             N *p = (struct N *)malloc(sizeof(struct N));
32             p->data = v;
33             p->next = p1->next;
34             p1->next = p;
35             return 1;
36         }
37     }
38     N *p = (struct N *)malloc(sizeof(struct N));
39     p->data = v;
40     p->next = p1->next;
41     p1->next = p;
42     return 1;
43 }
44 
45 void check(int i)
46 {
47     for(N *p = head[i]->next;p != NULL;p = p->next)
48     {
49         head[p->data]->n--;
50     }
51 }
52 
53 int q[510],j,hash[510];
54 
55 int main()
56 {
57     int n,m,u,v,i;
58     while(scanf("%d %d",&n,&m) != EOF)
59     {
60         init(n);
61         memset(hash,0,sizeof(hash));
62         for(i = 0;i < m; i++)
63         {
64             scanf("%d %d",&u,&v);
65             if(link(u,v))
66                 head[v]->n++;
67         }
68         for(i = 1,j = 0;i <= n && j < n; i++)
69         {
70             if(head[i]->n == 0  && !hash[i])
71             {
72                 check(i);
73                 hash[i] = 1;
74                 q[j++] = i;
75                 i = 0;
76             }
77         }
78         printf("%d",q[0]);
79         for(i = 1;i < j; i++)
80             printf(" %d",q[i]);
81         printf("\n");
82     }
83     return 0;
84 }