tarjan强连通分量 （模板）

#include<iostream>
#include<cstdio>

using namespace std;
const int MAXN = 10005;

struct Edge{
    int nxt,to;
}edge[10*MAXN];

int n,m,stack[MAXN],low[MAXN],dfn[MAXN];
int cnt,head[MAXN],col[MAXN],num,top,col_num;
bool vis[MAXN];

inline void add(int bg,int ed){
    edge[++cnt].to=ed;
    edge[cnt].nxt=head[bg];
    head[bg]=cnt;
}

inline void tarjan(int u){
    dfn[u]=low[u]=++num;
    vis[u]=1;
    stack[++top]=u;
    for(int i=head[u];i;i=edge[i].nxt){
        int v=edge[i].to;
        if(!dfn[v]){
            tarjan(v);
            low[u]=min(low[v],low[u]);
        }
        else if(vis[v])
            low[u]=min(low[u],dfn[v]);
    }
    if(dfn[u]==low[u]){
        vis[u]=0;
        col[u]=++col_num;
        while(stack[top]!=u){
            col[stack[top]]=col_num;
            printf("%d ",stack[top]);
            vis[stack[top--]]=0;
        }
        printf("%d\n",u);
        top--;
    }
}

int main(){
    scanf("%d%d",&n,&m);
    for(register int i=1;i<=m;i++){
        int x,y;
        scanf("%d%d",&x,&y);
        add(x,y);
    }
    for(register int i=1;i<=n;i++){
        if(!dfn[i]) tarjan(i);
    }
}