确定比赛名次(toposort)

http://acm.hdu.edu.cn/showproblem.php?pid=1285

 #include <stdio.h>
 #include <string.h>
 const int N=;
 int p[N][N],in[N];
 int n,m;
 void toposort()
 {
     for (int i = ; i <= n; i++)
     {
         for (int j = ; j <= n; j++)
         {
             if(in[j]==)
             {
                 if(i==)
                     printf("%d",j);
                 else
                     printf(" %d",j);
                 in[j]--;
                 for (int k = ; k <= n; k++)
                 {
                     if(p[j][k]==)
                         in[k]--;
                 }
                 break;
             }

         }
     }
 }
 int main()
 {
     while(~scanf("%d%d",&n,&m))
     {
         memset(p,,sizeof(p));
         memset(in,,sizeof(in));
         int p1,p2;
         while(m--)
         {
             scanf("%d%d",&p1,&p2);
             if(!p[p1][p2])
             {
                 p[p1][p2] = ;
                 in[p2]++;
             }
         }
         toposort();
         puts("");
     }
     return ;
 }