Tarjan algorithm [template]

1 #include<bits/stdc++.h>
 2  using  namespace std;
 3  const  int maxn= 100005 ;
 4  int cnt= 0 ; // Number of strongly connected components 
5  int stk[maxn]; // Temporarily store the traversed Point, throw out element 
6  when encountering low[x]==dfn[x] int dfn[maxn]; // Timestamp [Because each point belongs to at most one strongly connected component, it is also used to distinguish whether It already exists in a strongly connected component. If it exists, there is no need to continue to search down.] 
7  int low[maxn] // And the time of the earliest ancestor 
8  int vis[maxn]; // Mark this traversal process into the stack dot, also clear marked sigil when stk[] throws dot 
9  intsz[maxn]; // Number of elements in each strongly connected component 
10  int tim= 1 ;
 11  void tar( int x)
 12  {
 13      low[x]=dfn[x]=tim++ ;
 14      vis[x] = 1 ;
 15      stk[tot++]= x;
 16      if (! dfn[next[x]])
 17      {
 18          tar(next[x]);
 19          low[x]= min(low[x],low[next [x]]);
 20      }
 21      else  if (vis[next[x]])
 22      {
 23         low[x]= dfn[next[x]];
 24      }
 25      if (dfn[x]== low[x])
 26      {
 27          int xx;
 28          cnt++ ;
 29          do {
 30              xx=stk[--tot] ; // Throw element 
31              col[xx]=cnt; // Color block 
32              sz[cnt]++; // Number of elements in the strongly connected component where the element is located 
33              vis[xx]= 0 ; // clear flag 
34          } while (x!= xx);
 35      }
36 }
37 int main()
38 {
39     for(int i = 1 ; i <= n ; i++)
40     {
41         tar(i);
42     }
43     return 0;
44 }