1 #include <stdio.h>
 2 #include <stdlib.h>
 3 #include <string.h>
 4 #include <queue>
 5 #define MAX 10000+2
 6 using namespace std;
 7
 8 typedef struct node
 9 {
10     int x0;
11     struct node *next;
12 }node;
13
14 node s[MAX];
15
16 int d[MAX],e[MAX];
17
18 queue<int> p;
19
20 bool deal(int n)
21 {
22     int i,count;
23     node *f,*r;
24     while(!p.empty()) p.pop();
25     count=0;
26     for(i=1;i<=n;i++) if(!e[i]) {p.push(i);}
27     while(!p.empty())
28     {
29         i=p.front();
30         count++;
31         p.pop();
32         f=s[i].next;
33         while(f)
34         {
35             e[f->x0]--;
36             if(!e[f->x0])
37             {
38                 p.push(f->x0);
39                 d[f->x0]=d[f->x0]<(d[i]+1) ? (d[i]+1) : d[f->x0];
40             }
41             r=f;
42             f=f->next;
43             free(r);
44         }
45     }
46     if(n==count) return 1;
47     return 0;
48 }
49
50 void jadge(int n)
51 {
52     int i,ans;
53     ans=0;
54     for(i=1;i<=n;i++) ans+=d[i];
55     printf("%d\n",ans+888*n);
56 }
57
58 void insert(int x,int y)
59 {
60     node *f;
61     f=&s[x];
62     while(f->next)
63     {
64         if(f->x0==y) return ;
65     }
66     f->next=(node*)malloc(sizeof(node));
67     f->next->next=NULL;
68     f->next->x0=y;
69     e[y]++;
70 }
71
72 int main()
73 {
74     int n,m,i,x,y;
75     //freopen("data.txt","r",stdin);
76     while(scanf("%d %d",&n,&m)!=EOF)
77     {
78         for(i=1;i<=n;i++) {s[i].x0=i;s[i].next=NULL;}
79         memset(d,0,sizeof(d));
80         memset(e,0,sizeof(e));
81         for(i=0;i<m;i++)
82         {
83             scanf("%d %d",&y,&x);
84             insert(x,y);
85         }
86         if(!deal(n)) printf("-1\n");
87         else jadge(n);
88     }
89     return 0;
90 }

 1 #include <stdio.h>
 2 #include <stdlib.h>
 3 #include <string.h>
 4 #include <queue>
 5 #include <map>
 6 #include <vector>
 7 #include <algorithm>
 8 #define MAX (10000+2)
 9 using namespace std;
10
11 int head[MAX],tot,co[MAX],f[MAX];
12
13 typedef struct
14 {
15     int to;
16     int next;
17 }Node;
18
19 Node node[MAX<<1];
20
21 map<pair<int,int>,int> M;
22 queue<int> q;
23
24 int topo(int n)
25 {
26     int i,u,count;
27     while(!q.empty()) q.pop();
28     memset(f,0,sizeof(f));
29     count=0;
30     for(i=1;i<=n;i++)
31     {
32         if(!co[i])
33         {
34             f[i]=0;
35             q.push(i);
36         }
37     }
38     while(!q.empty())
39     {
40         u=q.front();
41         q.pop();
42         count++;
43         for(i=head[u];i!=-1;i=node[i].next)
44         {
45             co[node[i].to ]--;
46             if(co[node[i].to]==0)
47             {
48                q.push(node[i].to);
49                f[node[i].to]=f[u]+1 > f[node[i].to] ? f[u]+1 : f[node[i].to];
50             }
51         }
52     }
53     if(count<n) return 0;
54     return 1;
55 }
56
57 int main()
58 {
59     int n,m,i,sum;
60     pair<int,int> e;
61     //freopen("data.txt","r",stdin);
62     while(scanf("%d %d",&n,&m)!=EOF)
63     {
64         memset(head,-1,sizeof(head));
65         memset(co,0,sizeof(co));
66         memset(node,0,sizeof(node));
67         M.clear();
68         tot=0;
69         for(i=0;i<m;i++)
70         {
71             scanf("%d %d",&e.second,&e.first);    //first ==>right   second ==>left
72             if(M.count(e)<=0)
73             {
74                 M.insert(pair<pair<int,int>,int>(e,1));
75                 node[tot].to=e.second;
76                 node[tot].next=head[e.first];
77                 head[e.first]=tot++;
78                 co[e.second]++;
79             }
80         }
81         if(!topo(n)) printf("-1\n");
82         else
83         {
84             sum=0;
85             for(i=1;i<=n;i++) sum+=f[i];
86             sum+=n*888;
87             printf("%d\n",sum);
88         }
89     }
90     return 0;
91 }