CIA3 NOI接站（tarjan缩环+Floyd传递闭包+可相交最小路径覆盖）

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <stack>
using namespace std;
#define ll long long
#define N 210
#define M 1010
inline int read(){
int x=0,f=1;char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9') x=x*10+ch-'0',ch=getchar();
return x*f;
}
int tst,n,m,h
,h1
,num=1,scc=0,bel
,dfn
,low
,dfnum=0,ans=0,bf
;
bool inq
,mp

;
struct edge{
int to,next;
}data1[M],data[M<<2];
stack<int>qq;
inline void add(int x,int y){
data[++num].to=y;data[num].next=h[x];h[x]=num;
}
inline void tarjan(int x){
dfn[x]=low[x]=++dfnum;qq.push(x);inq[x]=1;
for(int i=h1[x];i;i=data1[i].next){
int y=data1[i].to;
if(!dfn[y]) tarjan(y),low[x]=min(low[x],low[y]);
else if(inq[y]) low[x]=min(low[x],dfn[y]);
}if(dfn[x]==low[x]){
++scc;while(1){
int y=qq.top();qq.pop();inq[y]=0;
bel[y]=scc;if(y==x) break;
}
}
}
inline bool find(int x){
for(int i=h[x];i;i=data[i].next){
int y=data[i].to;if(inq[y]) continue;
inq[y]=1;if(!bf[y]||find(bf[y])){bf[y]=x;return 1;}
}return 0;
}
int main(){
//  freopen("a.in","r",stdin);
tst=read();
while(tst--){
n=read();m=read();memset(h1,0,sizeof(h1));memset(h,0,sizeof(h));
num=1;scc=0;memset(dfn,0,sizeof(dfn));dfnum=0;memset(mp,0,sizeof(mp));
memset(inq,0,sizeof(inq));ans=0;memset(bf,0,sizeof(bf));
while(m--){
int x=read(),y=read();
data1[++num].to=y;data1[num].next=h1[x];h1[x]=num;
}for(int i=1;i<=n;++i) if(!dfn[i]) tarjan(i);num=1;
for(int x=1;x<=n;++x)
for(int i=h1[x];i;i=data1[i].next){
int y=data1[i].to;if(bel[y]!=bel[x]) mp[bel[x]][bel[y]]=1;
}
for(int k=1;k<=scc;++k)
for(int i=1;i<=scc;++i)
for(int j=1;j<=scc;++j)
mp[i][j]|=(mp[i][k]&mp[k][j]);
for(int i=1;i<=scc;++i)
for(int j=1;j<=scc;++j)
if(mp[i][j]) add(i,j);
for(int i=1;i<=scc;++i){
memset(inq,0,sizeof(inq));if(find(i)) ans++;
}printf("%d\n",scc-ans);
}
return 0;
}