poj1236/luogu2746 Network of Schools (tarjan)

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<algorithm>
 4 #define LL long long int
 5 using namespace std;
 6 const int maxn=110,maxm=10010;
 7 
 8 LL rd(){
 9     LL x=0;char c=getchar();int neg=1;
10     while(c<‘0‘||c>‘9‘){if(c==‘-‘) neg=-1;c=getchar();}
11     while(c>=‘0‘&&c<=‘9‘) x=x*10+c-‘0‘,c=getchar();
12     return x*neg;
13 }
14 
15 int N;
16 int eg[maxm][2],egh[maxn],ect,bel[maxn];
17 int dfn[maxn],low[maxn],stk[maxn],tot,pct,sct;
18 int tin,tout;
19 bool instk[maxn],in[maxn],out[maxn];
20 
21 void tarjan(int x){
22     dfn[x]=low[x]=++tot;stk[++sct]=x;instk[x]=1;
23     for(int i=egh[x];i!=-1;i=eg[i][1]){
24         int j=eg[i][0];
25         if(instk[j]) low[x]=min(low[x],dfn[j]);
26         else if(!dfn[j]){
27             tarjan(j);low[x]=min(low[x],low[j]);
28         }
29     }
30     if(dfn[x]==low[x]){
31         pct++;
32         while(sct){
33             instk[stk[sct]]=0;
34             bel[stk[sct]]=pct;
35             if(stk[sct--]==x) break;
36         }
37     }
38 }
39 
40 inline void adeg(int a,int b){
41     eg[ect][0]=b;eg[ect][1]=egh[a];egh[a]=ect++;
42 }
43 
44 int main(){
45     int i,j,k;
46     N=rd();memset(egh,-1,sizeof(egh));
47     for(i=1;i<=N;i++){
48         while(j=rd()) adeg(i,j);
49     }
50     for(i=1;i<=N;i++){
51         if(!dfn[i]) tarjan(i);
52     }
53     for(i=1;i<=N;i++){
54         for(j=egh[i];j!=-1;j=eg[j][1]){
55             k=eg[j][0];
56             int ii=bel[i],kk=bel[k];
57             if(ii!=kk){
58                 in[kk]=1;out[ii]=1;
59             }
60         }
61     }for(i=1;i<=pct;i++){
62         if(!in[i]) tin++;
63         if(!out[i]) tout++;
64     }
65     if(pct>1)printf("%d\n%d",tin,max(tin,tout));
66     else printf("1\n0");
67     
68 }