CF949 C Data Center Maintenance——边双连通分量

#include<iostream>
#include<cstdio>
#include<cstring>
#include<vector>
using namespace std;
int const maxn=1e5+5;
int n,m,h,a[maxn],hd[maxn],cr,ct,col[maxn],sta[maxn],top,dfn[maxn],low[maxn],tim,deg[maxn];
bool vis[maxn];
vector<int>scc[maxn];
struct N{
    int to,nxt;
    N(int t=0,int n=0):to(t),nxt(n) {}
}ed[maxn<<1];
void add(int x,int y){ed[++ct]=N(y,hd[x]); hd[x]=ct;}
void tarjan(int x)
{
    dfn[x]=low[x]=++tim; sta[++top]=x; vis[x]=1;
    for(register int i=hd[x];i;i=ed[i].nxt)
    {
        int u=ed[i].to;
        if(!dfn[u])
        {
            tarjan(u); low[x]=min(low[x],low[u]);
        }
        else if(vis[x])low[x]=min(low[x],dfn[u]);
    }
    if(low[x]==dfn[x])
    {
        cr++;
        while(sta[top]!=x)
        {
            int y=sta[top]; top--;
            vis[y]=0; col[y]=cr;
            scc[cr].push_back(y);
        }
        top--;//!
        vis[x]=0; col[x]=cr; scc[cr].push_back(x);
    }
}
int main()
{
    scanf("%d%d%d",&n,&m,&h);
    for(register int i=1;i<=n;i++)scanf("%d",&a[i]);
    for(register int i=1,x,y;i<=m;i++)
    {
        scanf("%d%d",&x,&y);
        if((a[x]+1)%h==a[y])add(x,y);
        if((a[y]+1)%h==a[x])add(y,x);
    }
    for(register int i=1;i<=n;i++)
        if(!dfn[i])tarjan(i);
    for(register int i=1;i<=n;i++)
        for(register int j=hd[i];j;j=ed[j].nxt)
        {
            int u=ed[j].to;
            if(col[i]!=col[u])deg[col[i]]++;
        }
    int mn=0x3f3f3f3f,tag;
    for(register int i=1;i<=cr;i++)
        if(!deg[i]&&scc[i].size()<mn)mn=scc[i].size(),tag=i;
    printf("%d\n",scc[tag].size());
    for(register int j=0;j<scc[tag].size();j++)
        printf("%d ",scc[tag][j]);
    return 0;
}