1 vector<int> G[MAXN];
2 int dfn[MAXN], low[MAXN], instk[MAXN], sccno[MAXN], ans[MAXN];
3 stack<int> S;
4 int Time, cnt ,n, res;
5 void Tarjan(int u)
6 {
7 dfn[u] = low[u] = ++Time;
8 S.push(u);
9 instk[u] = 1;
10 for (int i = 0; i < G[u].size(); ++i) {
11 int v = G[u][i];
12 if (!dfn[v]) {
13 Tarjan(v);
14 low[u] = min(low[u], low[v]);
15 }
16 else if (instk[v]) {
17 low[u] = min(low[u], dfn[v]);
18 }
19 }
20 if (low[u] == dfn[u]) {
21 cnt++;
22 int v;
23 do{
24 v = S.top();
25 S.pop();
26 instk[v] = 0;
27 sccno[v] = cnt;
28 } while (v != u);
29 }
30 }
31
32 void find_scc()
33 {
34 for (int i = 1; i <= n; ++i)
35 if (!dfn[i]) Tarjan(i);
36 }
