Tarjan强连通分量

Tarjan强连通分量

/*
*  Tarjan 强连通分量
*  INIT: vec[]为邻接表; stop, cnt, scnt置0; pre[]置-1;
*  CALL: for(i=0;i<n;++i)if(-1==pre[i])tarjan(i,n);
*/
const int V = 10010;

int stop, cnt, scnt;
int id[V], pre[V], low[V], s[V];
vector<int> vec[V];

void tarjan(int v, int n)   //  vertex: 0 ~ n-1
{
int t, minc = low[v] = pre[v] = cnt++;
vector<int>::iterator pv;
s[stop++] = v;
for (pv = vec[v].begin(); pv != vec[v].end(); ++pv)
{
if (-1 == pre[*pv])
{
tarjan(*pv, n);
}
if (low[*pv] < minc)
{
minc = low[*pv];
}
}
if (minc < low[v])
{
low[v] = minc;
return ;
}
do
{
id[t = s[--stop]] = scnt;
low[t] = n;
}
while (t != v);
++scnt;         // 强连通分量的个数
return ;
}