CF613D Kingdom and its Cities 虚树 + 树形DP

Code: 

#include<bits/stdc++.h>
#define ll long long  
#define maxn 300003 
#define RG register
using namespace std; 
inline int read()
{
    RG int x=0,t=1;RG char ch=getchar();
    while((ch<'0'||ch>'9')&&ch!='-')ch=getchar();
    if(ch=='-')t=-1,ch=getchar();
    while(ch<='9'&&ch>='0')x=x*10+ch-48,ch=getchar();
    return x*t;
}
inline void setIO(string s) 
{
	string in=s+".in", out=s+".out"; 
	freopen(in.c_str(),"r",stdin); 
}
int edges,tim,n;  
int hd[maxn], to[maxn<<1], nex[maxn<<1];  
inline void add(int u,int v) 
{
	nex[++edges]=hd[u],hd[u]=edges,to[edges]=v; 
}
int fa[maxn], top[maxn], dfn[maxn], hson[maxn], siz[maxn], dep[maxn]; 
void dfs1(int u,int ff)
{ 
	siz[u]=1,fa[u]=ff,dfn[u]=++tim,dep[u]=dep[ff]+1; 
	for(int i=hd[u];i;i=nex[i])
	{
		int v=to[i];
		if(v==ff) continue; 
		dfs1(v, u); 
		siz[u]+=siz[v]; 
		if(siz[v]>siz[hson[u]]) hson[u]=v;   
	}
} 
void dfs2(int u,int tp)
{
	top[u]=tp; 
	if(hson[u]) dfs2(hson[u], tp); 
	for(int i=hd[u];i;i=nex[i])
	{
		int v=to[i]; 
		if(v==fa[u]||v==hson[u]) continue; 
		dfs2(v,v);       
	}
} 
inline int LCA(int x,int y)
{
	while(top[x]!=top[y]) 
	{
		dep[top[x]] > dep[top[y]] ? x = fa[top[x]] : y = fa[top[y]]; 
	}
	return dep[x] < dep[y] ? x : y;   
}       
int tp; 
vector<int>G[maxn]; 
int arr[maxn],mk[maxn],S[maxn],g[maxn],f[maxn];           
int cmp(int i,int j) 
{
	return dfn[i]<dfn[j];              
}
inline void addvir(int u,int v)
{
	G[u].push_back(v); 
}
inline void insert(int x)
{ 
	if(tp<=1) { S[++tp]=x;  return; } 
	int lca=LCA(x, S[tp]); 
	if(lca==S[tp]) { S[++tp]=x; return; }  
	while(tp > 1 && dep[S[tp - 1]] >= dep[lca]) addvir(S[tp-1], S[tp]), --tp; 
	if(S[tp]!=lca) addvir(lca,S[tp]), S[tp]=lca;  
	S[++tp]=x;         
} 
void DP(int x)
{    
	g[x]=f[x]=0;
	for(int i=0;i<G[x].size();++i) 
	{  
		int v = G[x][i];       
		DP(v); 
		f[x]+=f[v];    
		g[x]+=g[v];   
	}                 
	if(mk[x]) f[x]+=g[x], g[x]=1; 
	else f[x]+=(g[x]>1), g[x]=(g[x]==1);               
	G[x].clear();  
}    
inline void work() 
{   
	int k=read();                 
	for(int i=1;i<=k;++i) arr[i]=read(), mk[arr[i]]=1; 
	sort(arr+1,arr+1+k,cmp);       
    for(int i=1;i<=k;++i) 
    	if(mk[arr[i]]&&mk[fa[arr[i]]])                       
    	{
    		for(int j=1;j<=k;++j) mk[arr[j]]=0; 
    		printf("-1\n"); 
    		return; 
    	}      
    tp=0;   
    if(arr[1]!=1) S[tp=1]=1; 
    for(int i=1;i<=k;++i) insert(arr[i]); 
    while(tp > 1) addvir(S[tp - 1], S[tp]), --tp;       
    DP(1);         
    printf("%d\n",f[1]);   
    for(int j=1;j<=k;++j) mk[arr[j]]=0;
}
int main()
{
	// setIO("input");  
	n=read(); 
	for(int i=1,a,b;i<n;++i) 
	{
		a=read(),b=read(); 
		add(a,b), add(b,a);                                 
	} 
	dfs1(1,0), dfs2(1,1); 
	int Q; 
	Q=read(); 
	for(int i=1;i<=Q;++i) work(); 
	return 0; 
}