BZOJ 3083 遥远的国度 树链剖分+线段树

有换根的树链剖分的裸题.

在换根的时候注意讨论.

注意数据范围要开unsigned int或longlong

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<ctime>
#include<string>
#include<iomanip>
#include<algorithm>
#include<map>
using namespace std;
#define LL long long
#define FILE "dealing"
#define up(i,j,n) for(LL i=j;i<=n;++i)
#define db double
#define uint unsigned int
#define eps 1e-12
#define pii pair<LL,LL>
LL read(){
	LL x=0,f=1,ch=getchar();
	while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
	while(ch>=‘0‘&&ch<=‘9‘){x=(x<<1)+(x<<3)+ch-‘0‘;ch=getchar();}
	return f*x;
}
const LL maxn=800010,maxm=20000,limit=1e6,mod=(LL)(7+1e9+0.1);
const db inf=(1e18);
template<class T>bool cmax(T& a,T b){return a<b?a=b,true:false;}
template<class T>bool cmin(T& a,T b){return a>b?a=b,true:false;}
template<class T>T min(T& a,T& b){return a<b?a:b;}
template<class T>T max(T& a,T& b){return a>b?a:b;}
LL n,m,root;
LL v[maxn],id[maxn],pre[maxn],low[maxn],dfs_clock=0,top[maxn],dep[maxn],fa[maxn][30];
struct node{
	LL y,next;
}e[maxn];
LL len,linkk[maxn];
void insert(LL x,LL y){
	e[++len].y=y;
	e[len].next=linkk[x];
	linkk[x]=len;
}
namespace Seg_tree{
	LL Min[maxn],L,R,key,flag[maxn],f[maxn];
	void updata(LL x){
		Min[x]=min(Min[x<<1],Min[x<<1|1]);
	}
	void add(LL x,LL d){
		Min[x]=d;
		f[x]=1;
		flag[x]=d;
	}
	void pushdown(LL x){
		if(f[x]){
			f[x]=0;
			add(x<<1,flag[x]);
			add(x<<1|1,flag[x]);
			flag[x]=0;
		}
	}
	void change(LL l,LL r,LL x){
		if(l>R||r<L)return;
		if(l>=L&&r<=R){add(x,key);return;}
		LL mid=(l+r)>>1;
		pushdown(x);
		change(l,mid,x<<1);
		change(mid+1,r,x<<1|1);
		updata(x);
	}
	void Change(LL l,LL r,LL K){
		L=l,R=r,key=K;
		change(1,n,1);
	}
	LL query(LL l,LL r,LL x){
		if(l>R||r<L)return (LL)(1e12);
		if(l>=L&&r<=R)return Min[x];
		LL mid=(l+r)>>1;
		pushdown(x);
		return min(query(l,mid,x<<1),query(mid+1,r,x<<1|1));
	}
	LL Query(LL Lef,LL Rig){
		L=Lef,R=Rig;
		return query(1,n,1);
	}
	void build(LL l,LL r,LL x){
		if(l==r){
			Min[x]=v[id[l]];
			return;
		}
		LL mid=(l+r)>>1;
		build(l,mid,x<<1);
		build(mid+1,r,x<<1|1);
		updata(x);
	}
}
namespace shupou{
	LL son[maxn],siz[maxn];
	void dfs1(LL x){
		siz[x]=1;
		for(LL i=linkk[x];i;i=e[i].next){
			if(e[i].y==fa[x][0])continue;
			fa[e[i].y][0]=x;
			dep[e[i].y]=dep[x]+1;
			dfs1(e[i].y);
			siz[x]+=siz[e[i].y];
			if(siz[e[i].y]>siz[son[x]])son[x]=e[i].y;
		}
	}
	void dfs2(LL x){
		pre[x]=++dfs_clock;
		if(son[x]){
			top[son[x]]=top[x];
			dfs2(son[x]);
		}
		for(LL i=linkk[x];i;i=e[i].next){
			if(e[i].y==fa[x][0]||e[i].y==son[x])continue;
			top[e[i].y]=e[i].y;
			dfs2(e[i].y);
		}
		low[x]=dfs_clock;
	}
	void solve(){
		dfs1(1);
		top[1]=1;
		dfs2(1);
	}
}
namespace QUERY{
	void change(LL x,LL y,LL key){//将x-y改成key
		while(true){
			if(dep[x]>dep[y])swap(x,y);
			LL f1=top[x],f2=top[y];
			if(f1==f2){
				Seg_tree::Change(pre[x],pre[y],key);
				return;
			}
			if(dep[f1]>dep[f2])swap(x,y),swap(f1,f2);
			Seg_tree::Change(pre[f2],pre[y],key);
			y=fa[f2][0];
		}
	}
	LL query(LL x){
		if(x==root)return Seg_tree::Min[1];
		if(pre[x]>=pre[root]&&pre[x]<=low[root])return Seg_tree::Query(pre[x],low[x]);
		if(dep[x]>=dep[root])return Seg_tree::Query(pre[x],low[x]);
		LL y=root;
		for(LL i=23;i>=0;i--)if(dep[y]-(dep[x]+1)>=(1<<i))y=fa[y][i];
		if(fa[y][0]==x)return min(Seg_tree::Query(1,pre[y]-1),Seg_tree::Query(low[y]+1,n));
		return Seg_tree::Query(pre[x],low[x]);
	}
};
namespace sol{
	void solve(){
		n=read(),m=read();
		up(i,2,n){
			LL x=read(),y=read();
			insert(x,y);insert(y,x);
		}
		up(i,1,n)v[i]=read();
		root=read();
		shupou::solve();
		up(j,1,23)up(i,1,n)fa[i][j]=fa[fa[i][j-1]][j-1];
		up(i,1,n)id[pre[i]]=i;
		Seg_tree::build(1,n,1);
		up(i,1,m){
			LL ch=read();
			if(ch==1)root=read();
			if(ch==2){
				LL x=read(),y=read(),v=read();
				QUERY::change(x,y,v);
			}
			if(ch==3){
				LL x=read();
				LL d=0;
				printf("%lld\n",d=QUERY::query(x));
			}
		}
	}
}
int main(){
	freopen(FILE".in","r",stdin);
	freopen(FILE".out","w",stdout);
	sol::solve();
	return 0;
}