強連通分量SCC模版（LRJ）

#include<cstdio>#include<algorithm>#include<vector>#include<cstring>#include<stack>using namespace std;const int maxn = 1000 + 10;//圖中節點編號從0開始，scc從1開始vector<int> G[maxn];int pre[maxn], lowlink[maxn], sccno[maxn], dfs_clock, scc_cnt;stack<int> S;void dfs(int u) {  pre[u] = lowlink[u] = ++dfs_clock;  S.push(u);  for(int i = 0; i < G[u].size(); i++) {    int v = G[u][i];    if(!pre[v]) {      dfs(v);      lowlink[u] = min(lowlink[u], lowlink[v]);    } else if(!sccno[v]) {      lowlink[u] = min(lowlink[u], pre[v]);    }  }  if(lowlink[u] == pre[u]) {    scc_cnt++;    for(;;) {      int x = S.top(); S.pop();      sccno[x] = scc_cnt;      if(x == u) break;    }  }}void find_scc(int n) {  dfs_clock = scc_cnt = 0;  memset(sccno, 0, sizeof(sccno));  memset(pre, 0, sizeof(pre));  for(int i = 0; i < n; i++)    if(!pre[i]) dfs(i);}