FIG given topological sort is determined whether there is a legitimate sequence own topology oj1393

1  // topological sort to determine whether there ring 
2 #include <cstdio>
 . 3 #include <algorithm>
 . 4 #include < String .h>
 . 5 #include <math.h>
 . 6 #include <Queue>
 . 7  the using  namespace STD;
 . 8 typedef Long  Long LL;
 . 9  const  int MAXN 1E2 + = 10 ;
 10  int G [MAXN] [MAXN];
 . 11  int  in [MAXN];
 12 is  void the init ()
 13 is  {
 14      Memset (G, 0 ,the sizeof (G));   // FIG. 
15      Memset ( in , 0 , the sizeof ( in ));   // Penetration 
16  }
 . 17  int Toposort ( int n-)
 18 is  {
 . 19      int AIM;
 20 is      int COT = 0 ;
 21 is      int In Flag = 1 ;   // 1 when an ordered
 22      // every cycle, to identify the degree of zero point, if you can not find prove ring (this force memory)
 23      // once located, this point the connected side of the other endpoint 1;
 24      // the algorithm ends 
25     for(int i=1;i<=n;i++){
26         int num=0;
27         for(int j=1;j<=n;j++)
28             if(!in[j]){
29                 num++;
30                 aim=j;
31                 break;
32             }
33         if(!num) return 0;  //有环；
34         in[aim]=-1;
35         for(int j=1;j<=n;j++)
36             if(G[aim][j]) in[j]--;
37     }
38     return flag;
39 
40 }
41 int main()
42 {
43     int n,m;
44     while(scanf("%d%d",&n,&m)!=EOF){
45         init();  //初始化
46         for(int i=1;i<=m;i++){
47             int u,v;
48              Scanf ( " % D% D " , & U, & v);
 49              G [U] [v] = . 1 ;
 50              in [v] ++;   // U v to v edged so that the penetration ++; 
51 is          }
 52 is          int In Flag = Toposort (n-);
 53 is          IF (In Flag == . 1 ) the printf ( " YES \ n- " );
 54 is          the else the printf ( " NO \ n- " );
 55      }
 56 is      return  0 ;
 57 is }

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