Kosaraju算法——强连通分量

#include <bits/stdc++.h>
using namespace std;

const int maxn=100000+15;
int n,m;
vector <int> edge[maxn],rev[maxn];
int tim,rank[maxn],ref[maxn];
bool boo[maxn];
int color[maxn],tot;
int dfs1(int now)
{
    if (boo[now]) return 0;
    boo[now]=true;
    for (int i=0;i<edge[now].size();dfs1(edge[now][i]),i++);
    rank[now]=++tim;
    ref[tim]=now;
    return 0;
}
int dfs2(int now)
{
    if (color[now]!=0) return 0;
    color[now]=tot;
    for (int i=0;i<rev[now].size();dfs2(rev[now][i]),i++);
    return 0;
}
int main()
{
    freopen("ko.in","r",stdin);
    scanf("%d%d",&n,&m);
    for (int i=1;i<=m;i++)
    {
        int x,y;
        scanf("%d%d",&x,&y);
        edge[x].push_back(y);
        rev[y].push_back(x);
        }
    for (int i=1;i<=n;i++)
     if (!boo[i]) dfs1(i);
    for (int i=n;i>=1;i--)
     if (color[ref[i]]==0)
     {
            tot++;
            dfs2(ref[i]);
            }
    for (int i=1;i<=n;i++) 
     printf("%d ",color[i]);
    return 0;
}