【COGS1298】通讯问题

#include <cstdio>
#include <iostream>
#include<algorithm>
#define N 200
using namespace std;
struct edge
{
    int to,next;
}e[N*N];
struct node
{
    int c[N],size;
}p[N];
int dfn[N],Low[N],sz[N];
int index,Count;
bool instack[N];
int s[N],top;
int head [N];
int cnt;
void ins(int u,int v)
{
    e[++cnt].to = v; e[cnt].next = head[u]; head[u] = cnt; 
}
void tarjan(int k){
    
    dfn[k]=Low[k]=++index;
    instack[k]=true; s[++top]=k;
    for (int i=head[k];i;i=e[i].next)
    {
        int j=e[i].to;
        if(dfn[j]==0){
            tarjan(j);
            Low[k]=min(Low[k],Low[j]);
        }else if(instack[j]) Low[k]=min(Low[k],dfn[j]);
    }
    if(dfn[k]==Low[k]) 
    {
        int j;
        Count++;
        do{
            j=s[top--]; instack[j]=false;
            p[Count].size++;
            sz[p[Count].size] = j;
        }while(j!=k);
        sort(sz+1,sz+p[Count].size+1);
        for (int i=1;i<=p[Count].size;i++)
            p[Count].c[i] = sz[i];
    }
}
int cmp(const node &a,const node &b)
{
    return a.c[1] < b.c[1];
}
int cmp2(const int &a,const int &b)
{
    return a<b;
}
int main(){
    int m,u,v,n=0;
    freopen("jdltt.in","r",stdin);
    freopen("jdltt.out","w",stdout);
    scanf("%d",&n);
    while (scanf("%d%d",&u,&v)==2)
        ins(u,v);
    for(int i=1;i<=n;i++)
        if(dfn[i]==0)
            tarjan(i);
    sort(p+1,p+1+Count,cmp);
    printf("%d\n",Count);
    for(int i=1;i<=Count;i++)
    {
        for (int j=1;j<=p[i].size;j++)
            printf("%d ",p[i].c[j]);
        printf("\n");
    }
    return 0;
}