【模板】树链剖分

.
.
.
.
.
分析
树剖+线段树

(我的代码太丑了，打了170+行)

.
.
.
.
.
程序：

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
using namespace std;

struct edge
{
	int to,from;
}e[500010];

int head[500010],n,size[500010],dep[500010],fa[500010],id[500010],a[500010];
int rk[500010],top[500010],son[500010],cnt=0,tot=0,sum[500010],p,lazy[500010];

void add(int x,int y)
{
	e[++cnt].to=y;e[cnt].from=head[x];head[x]=cnt;
	e[++cnt].to=x;e[cnt].from=head[y];head[y]=cnt;
}

void dfs1(int x,int father)
{
	fa[x]=father;
	dep[x]=dep[father]+1;
	size[x]=1;
	for (int i=head[x];i;i=e[i].from)
		if (e[i].to!=father)
		{
			dfs1(e[i].to,x);
			size[x]+=size[e[i].to];
			if (size[e[i].to]>size[son[x]]) son[x]=e[i].to;
		}
}

void dfs2(int x,int father)
{
	id[x]=++tot;
	rk[tot]=x;
	top[x]=father;
	if (son[x]) dfs2(son[x],father);
	for (int i=head[x];i;i=e[i].from)
		if (e[i].to!=son[x]&&e[i].to!=fa[x]) dfs2(e[i].to,e[i].to);
}

void build(int l,int r,int d)
{
	if (l==r)
	{
		sum[d]=a[rk[l]]%p;
		return;
	}
	int mid=(l+r)/2;
	build(l,mid,d*2);
	build(mid+1,r,d*2+1);
	sum[d]=(sum[d*2]+sum[d*2+1])%p;
}

void pushdown(int l,int r,int d)
{
	int mid=(l+r)/2;
	lazy[d*2]=(lazy[d*2]+lazy[d])%p;
	lazy[d*2+1]=(lazy[d*2+1]+lazy[d])%p;
	sum[d*2]=(sum[d*2]+lazy[d]*(mid-l+1))%p;
	sum[d*2+1]=(sum[d*2+1]+lazy[d]*(r-mid))%p;
	lazy[d]=0;
}

void update(int l,int r,int d,int x,int y,int z)
{
	if (x<=l&&y>=r)
	{
		sum[d]=(sum[d]+z*(r-l+1))%p;
		lazy[d]=(lazy[d]+z)%p;
		return;
	}
	if (l>y||r<x) return;
	int mid=(l+r)/2;
	if (lazy[d]!=0) pushdown(l,r,d);
	if (mid>=x) update(l,mid,d*2,x,y,z);
	if (mid<y) update(mid+1,r,d*2+1,x,y,z);
	sum[d]=(sum[d*2]+sum[d*2+1])%p;
}

int querysum(int l,int r,int d,int x,int y)
{
	int ans=0,mid=(l+r)/2;
	if (x<=l&&r<=y) return sum[d]%p;
	if (l>y||r<x) return 0;
	if (lazy[d]) pushdown(l,r,d);
	if (x<=mid) ans=(ans+querysum(l,mid,d*2,x,y))%p;
	if (y>mid) ans=(ans+querysum(mid+1,r,d*2+1,x,y))%p;
	sum[d]=(sum[d*2]+sum[d*2+1])%p;
	return ans%p;
}

int getsum(int x,int y)
{
	int ans=0,fx=top[x],fy=top[y];
	while (fx!=fy)
	{
		if (dep[fx]<dep[fy])
		{
			swap(x,y);
			swap(fx,fy);
		}
		ans=(ans+querysum(1,tot,1,id[fx],id[x]))%p;
		
		x=fa[fx];
		fx=top[x];
	}
	if (id[x]>id[y]) swap(x,y);
	ans=(ans+querysum(1,tot,1,id[x],id[y]))%p;
	return ans%p;
}

void work1(int x,int y,int z)
{
	int fx=top[x],fy=top[y];
    while (fx!=fy)
    {
        if (dep[fx]<dep[fy])
        {
        	swap(x,y);
			swap(fx,fy);
		}
        update(1,tot,1,id[fx],id[x],z);
        x=fa[fx];
		fx=top[x];
    }
    if (id[x]>id[y]) swap(x,y);
    update(1,tot,1,id[x],id[y],z);
}

int main()
{
	int m,r;
	scanf("%d%d%d%d",&n,&m,&r,&p);
	for (int i=1;i<=n;i++)
		scanf("%d",&a[i]);
	for (int i=1;i<=n-1;i++)
	{
		int x,y;
		scanf("%d%d",&x,&y);
		add(x,y);
	}
	dfs1(r,0);
	fa[r]=1;
	dep[r]=1;
	dfs2(r,r);
	build(1,n,1);
	while (m--)
	{
		int k,x,y,z;
		scanf("%d",&k);
		if (k==1)
		{
			scanf("%d%d%d",&x,&y,&z);
			work1(x,y,z%p);
		}
		if (k==2)
		{
			scanf("%d%d",&x,&y);
			printf("%d\n",getsum(x,y));
		}
		if (k==3)
		{
			scanf("%d%d",&x,&y);
			update(1,n,1,id[x],id[x]+size[x]-1,y%p);
		}
		if (k==4)
		{
			scanf("%d",&x);
			printf("%d\n",querysum(1,n,1,id[x],id[x]+size[x]-1));
		}
	}
	return 0;
}