强连通分量个数的tarjan算法

/*
强连通分量个数tarjan算法
*/
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;

const int maxV=1000,maxE=1000000;

struct Edge
{
int to,next;
}edge[maxE];

int Adj[maxV],Size;

void init()
{
Size=0;
memset(Adj,-1,sizeof(Adj));
}

void Add_Edge(int u,int v)
{
edge[Size].to=v; edge[Size].next=Adj[u]; Adj[u]=Size++;
}

int Low[maxV],DFN[maxV],Stack[maxV],Belong[maxV];
int Index,top,scc,n;

bool Instack[maxV]; int num[maxV];

void tarjan(int u)
{
int v;
Low[u]=DFN[u]=++Index;
Stack[top++]=u;
Instack[u]=true;
for(int i=Adj[u];~i;i=edge[i].next)
{
v=edge[i].to;
if(!DFN[v])
{
tarjan(v);
Low[u]=min(Low[u],Low[v]);
}
else if(Instack[v])
{
Low[u]=min(Low[u],DFN[v]);
}
}

if(Low[u]==DFN[u])
{
scc++;
do
{
v=Stack[--top];
Instack[v]=false;
num[scc]++;
Belong[v]=scc;
}while(v!=u);
}
}

void solve(int n)
{
memset(DFN,0,sizeof(DFN));
memset(Instack,false,sizeof(Instack));
memset(num,0,sizeof(num));

Index=scc=top=0;

for(int i=1;i<=n;i++)
{
if(!DFN[i]) tarjan(i);
}
}

int main()
{
int m;
while(scanf("%d%d",&n,&m)!=EOF&&n)
{
init();
int a,b;
for(int i=0;i<m;i++)
{
scanf("%d%d",&a,&b);
Add_Edge(a,b);
}

solve(n);

cout<<"scc: "<<scc<<endl;

for(int i=1;i<=scc;i++) cout<<num[i]<<"--";
cout<<endl;

for(int i=1;i<=n;i++)
{
cout<<"DFN: "<<DFN[i]<<" , Low: "<<Low[i]<<"     "<<Belong[i]<<endl;
}
cout<<endl;
}
return 0;
}