4296: [PA2015]Mistrzostwa 图的遍历

dfs一波

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define N 200005
using namespace std;
int n,m,d,cnt;
int q[N],ans[N],du[N],head[N];
int next[N<<1],list[N<<1];
bool vis[N];
inline int read()
{
    int a=0,f=1; char c=getchar();
    while (c<'0'||c>'9') {if (c=='-') f=-1; c=getchar();}
    while (c>='0'&&c<='9') {a=a*10+c-'0'; c=getchar();}
    return a*f;
}
inline void insert(int x,int y)
{
    next[++cnt]=head[x];
    head[x]=cnt;
    list[cnt]=y;
    du[y]++;
}
void dfs(int x)
{
    vis[x]=true;
    q[++q[0]]=x;
    for (int i=head[x];i;i=next[i])
        if (!vis[list[i]]) dfs(list[i]);
}
int main()
{
    n=read(); m=read(); d=read();
    for (int i=1;i<=m;i++)
    {
        int u=read(),v=read();
        insert(u,v); insert(v,u);
    }
    int t=0,w=0;
    for (int i=1;i<=n;i++)
        if (du[i]<d) q[++w]=i;
    while (t<w)
    {
        int x=q[++t];
        vis[x]=true;
        for (int i=head[x];i;i=next[i])
            if (--du[list[i]]==d-1) q[++w]=list[i]; 
    }
    for (int i=1;i<=n;i++)
        if (!vis[i])
        {
            q[0]=0;
            dfs(i);
            if (q[0]>ans[0]) 
                for (int i=0;i<=q[0];i++) 
                    ans[i]=q[i];
        }
    if (!ans[0]) puts("NIE");
    else
    {
        printf("%d\n",ans[0]);
        sort(ans+1,ans+ans[0]+1);
        for (int i=1;i<=ans[0];i++)
            printf("%d ",ans[i]);
    }
    return 0;
}