P3384 【模板】轻重链剖分/树链剖分

Archie

树链刨分之后很显然就成了一条一条的链

那么用线段树维护一下就行了

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int n,m,r,pp;
struct e{
	int to;
	int ne;
	int k;
}ed[200005];
int x,y,z,f;
int p;
int head[100005];
int son[100005];
int dep[100005];
int sd[100005];
int siz[100005];
int top[100005];
int fa[100005];
int dfn[100005];
int rnk[100005];
void add(int f,int to){
	p++;
	ed[p].ne=head[f];
	ed[p].to=to;
	head[f]=p;
}
int tree[400001];
int lazy[400001];
void pushdown(int R,int l,int r){
	if(lazy[R]){
		lazy[R<<1]+=lazy[R];
		lazy[R<<1|1]+=lazy[R];
		int mid= (l+r)>>1;
		tree[R<<1]+=lazy[R]*(mid-l+1)%pp;
		tree[R<<1|1]+=lazy[R]*(r-mid)%pp;
		lazy[R]=0;
	}
}
void pushup(int r){
	tree[r]=tree[r<<1]+tree[r<<1|1]; 
}
void add(int root,int L,int R,int l,int r,int v){
	if(l<=L&&r>=R){
		lazy[root]+=v;
		tree[root]+=(R-L+1)*v%pp;
		return ;
	}
	pushdown(root,L,R);
	int mid=(L+R)>>1;
	if(l<=mid) add(root<<1,L,mid,l,r,v);
	if(r>mid) add(root<<1|1,mid+1,R,l,r,v);
	pushup(root);
}
int query(int root,int L,int R,int l,int r){
	if(l<=L&&r>=R){
		return tree[root];
	}
	int mid=(L+R)>>1,ans=0;
	pushdown(root,L,R);
	ans%=pp;
		if(l<=mid) ans+=query(root<<1,L,mid,l,r)%pp;
		ans%=pp;
		if(r>mid) ans+=query(root<<1|1,mid+1,R,l,r)%pp;
	//pushup(root);
		return ans%pp;
}
void dfs(int no,int f){
	son[no]=-1;
	siz[no]=1;
	fa[no]=f;
	dep[no]=dep[f]+1;
	
	for(int i=head[no];i;i=ed[i].ne){
		if(ed[i].to==f) continue;
		dfs(ed[i].to,no);
		siz[no]+=siz[ed[i].to];
	
		if(son[no]==-1||siz[ed[i].to]>siz[son[no]]){
			son[no]=ed[i].to;
		}
	}
}
int cnt;
void dfs2(int no,int to){
//	cout<<no<<" "<<to<<endl; 
	cnt++;
	dfn[no]=cnt;
	top[no]=to;
	rnk[cnt]=no;
	sd[no]=dfn[no];
	if(-1==son[no]) return ;
	dfs2(son[no],to);
		sd[no]=max(sd[no],sd[son[no]]);
	for(int i=head[no];i;i=ed[i].ne){
		if(ed[i].to==fa[no]||ed[i].to==son[no]) continue;
		dfs2(ed[i].to,ed[i].to);
		sd[no]=max(sd[no],sd[ed[i].to]);
	}
	
}
void work1(){
		while(top[x]!=top[y]){
			if(dep[top[x]]>=dep[top[y]]){ 
			add(1,1,n,dfn[top[x]],dfn[x],z);
				x=fa[top[x]];
				
			}else{
				add(1,1,n,dfn[top[y]],dfn[y],z);
				y=fa[top[y]];
				
			}
		} 
		if(dep[x]>dep[y]){
			add(1,1,n,dfn[y],dfn[x],z);
		}else{
			add(1,1,n,dfn[x],dfn[y],z);
		}
} 
void work2(){
	int ans=0;
		while(top[x]!=top[y]){
			if(dep[top[x]]>=dep[top[y]]){ 
				ans+=query(1,1,n,dfn[top[x]],dfn[x])%pp;
				ans%=pp;
				x=fa[top[x]];
				
			}else{
				ans+=query(1,1,n,dfn[top[y]],dfn[y])%pp;
				ans%=pp;
				y=fa[top[y]];
			}
		} 
		if(dep[x]>dep[y]){
			ans+=query(1,1,n,dfn[y],dfn[x])%pp;
			ans%=pp;
		}else{
			ans+=query(1,1,n,dfn[x],dfn[y])%pp;
			ans%=pp;
		}
		cout<<ans%pp<<endl;
} 
int fr[1000001];
int main(){
	scanf("%d%d%d%d",&n,&m,&r,&pp);
	for(int i=1;i<=n;++i){
		scanf("%d",&fr[i]);
	}
	for(int i=1;i<n;++i){
		scanf("%d%d",&x,&y);
		add(x,y);
		add(y,x);
	} 
	dep[r]=1;
	dfs(r,r);
	dfs2(r,r);
	for(int i=1;i<=n;++i){
		add(1,1,n,dfn[i],dfn[i],fr[i]);
	}
	while(m--){
		scanf("%d",&f);
		if(f==1){
			scanf("%d%d%d",&x,&y,&z);
			z%=pp;
			work1();
		}
		if(f==2){
			scanf("%d%d",&x,&y);
			work2(); 
		}
		if(f==3) {
			scanf("%d%d",&x,&z);
			z%=pp;
			add(1,1,n,dfn[x],sd[x],z);
		}
		if(f==4) {
			scanf("%d",&x);
			cout<<query(1,1,n,dfn[x],sd[x])%pp<<endl;;
		}
	}
	return 0;
}