RT
照着日报打的,打错了/kk
求大佬修改
#include<iostream>
#include<vector>
#define root 1
using namespace std;
int dfn[10010],low[10010],cnt=0,cl=0,stack[10010],top;
int color[10010];//染色数组
int num[10010];//大小
bool vis[10010];//是否入了栈
inline int min(int x,int y){return ((x<y)?(x):(y));};
vector<int>gra[10010];
inline void tarjan(int u)
{
dfn[u]=low[u]=++cnt;
stack[top++]=u,vis[u]=1;
for(int p=0;p<gra[u].size();p++)
{
if(!dfn[gra[u][p]])
{
tarjan(dfn[gra[u][p]]);
low[gra[u][p]]=min(low[gra[u][p]],low[u]);
}
else
if(!vis[gra[u][p]])
low[gra[u][p]]=min(low[gra[u][p]],low[u]);
}
if(dfn[u]==low[u])
{
vis[u]=0,color[u]=++cl;
while(stack[top]!=u)
{
num[cl]++;
color[stack[top]]=cl;
vis[stack[top--]]=0;
}
top--;
}
}
int main()
{
int n,m,ans=0;
cin>>n>>m;
for(int p=1,x,y;p<=m;p++)
cin>>x>>y,gra[x].push_back(y);
tarjan(root);
for(int p=1;p<=n;p++)
if(!dfn[p])
tarjan(p);
for(int p=1;p<=n;p++)
if(num[p]>1)
ans++;
cout<<ans<<endl;
}