Luogu P2590 [ZJOI2008]树的统计

P2590 [ZJOI2008]树的统计

三种操作：

I. CHANGE u t : 把结点u的权值改为t

II. QMAX u v: 询问从点u到点v的路径上的节点的最大权值

III. QSUM u v: 询问从点u到点v的路径上的节点的权值和

简单树剖w（天天刷水的\(1e3+7\)）

其实就是树剖板子多配一个线段树维护区间最值

#include <algorithm>
#include <iostream>
#include <cstring>
#include <cstdio>
#include <cmath>
using namespace std;
#define MAXN 30233
int n,m,r;

int tot=0,cnt=0;

int ans[MAXN<<2],umax[MAXN<<2];

struct qwq
{
	int nex,to;
}e[MAXN<<1];
int h[MAXN];

int w1[MAXN],w2[MAXN];

int dep[MAXN],top[MAXN],siz[MAXN],fa[MAXN],id[MAXN],son[MAXN];

void add(int x,int y)
{
	e[++tot].to=y;
	e[tot].nex=h[x];
	h[x]=tot;
}

//dfs_str
inline void dfs1(int x,int f,int dept)
{
	dep[x]=dept;
	fa[x]=f;
	siz[x]=1;
	int mx=-1;
	for (int i=h[x],y;i;i=e[i].nex)
	{
		y=e[i].to;
		if (y==f) continue;
		dfs1(y,x,dept+1);
		siz[x]+=siz[y];
		if (siz[y]>mx)
		{
			son[x]=y;
			mx=siz[y];
		}
	}
}
inline void dfs2(int x,int ft)
{
	id[x]=++cnt;
	w2[cnt]=w1[x];
	top[x]=ft;
	if (!son[x]) return;
	dfs2(son[x],ft);
	for (int i=h[x],y;i;i=e[i].nex)
	{
		y=e[i].to;
		if (y==fa[x]||y==son[x]) continue;
		dfs2(y,y);
	}
}
//dfs_end.
//segment_tree
#define inf -2000000000
#define mid ((l+r)>>1)
#define leftson cur<<1
#define rightson cur<<1|1
#define push_up umax[cur]=max(umax[leftson],umax[rightson]); ans[cur]=ans[leftson]+ans[rightson]
inline void build(int cur,int l,int r)
{
	if (l==r)
	{
		umax[cur]=ans[cur]=w2[l];
		return;
	}
	build(leftson,l,mid);
	build(rightson,mid+1,r);
	push_up;
}
inline void change(int cur,int l,int r,int qcur,int del)
{
	if (l==r)
	{
		ans[cur]=umax[cur]=del;
		return;
	}
	if (qcur<=mid) change(leftson,l,mid,qcur,del);
	else change(rightson,mid+1,r,qcur,del);
	push_up;
}
inline int queryans(int cur,int l,int r,int ql,int qr)
{
	if (ql<=l&&r<=qr)
	{
		return ans[cur];
	}
	int answ=0;
	if (ql<=mid) answ+=queryans(leftson,l,mid,ql,qr);
	if (qr>mid) answ+=queryans(rightson,mid+1,r,ql,qr);
	push_up;
	return answ; 
}
inline int querymax(int cur,int l,int r,int ql,int qr)
{
	if (ql<=l&&r<=qr)
	{
		return umax[cur];
	}
	int answ=inf;
	if (ql<=mid) answ=max(answ,querymax(leftson,l,mid,ql,qr));
	if (qr>mid) answ=max(answ,querymax(rightson,mid+1,r,ql,qr));
	push_up;
	return answ;
}
//seg_tree_end.
int query_ans(int x,int y)
{
	int answ=0;
	while (top[x]!=top[y])
	{
		if (dep[top[x]]<dep[top[y]]) swap(x,y);
		answ+=queryans(1,1,n,id[top[x]],id[x]);
		x=fa[top[x]];
	}
	if (dep[x]>dep[y]) swap(x,y);
	answ+=queryans(1,1,n,id[x],id[y]);
	return answ;
}
int query_max(int x,int y)
{
	int answ=inf;
//	printf("qwq1\n");
	while (top[x]!=top[y])
	{
		if (dep[top[x]]<dep[top[y]]) swap(x,y);
//		printf("qwq2\n");
		answ=max(answ,querymax(1,1,n,id[top[x]],id[x]));
//		printf("\n\n::::::%d %d\n\n",id[top[x]],id[x]);
//		printf("qwq3\n");
		x=fa[top[x]];
	}
	if (dep[x]>dep[y]) swap(x,y);
	answ=max(answ,querymax(1,1,n,id[x],id[y]));
//	printf(":::qwqwqwqwqwq::;%d %d\n",id[x],id[y]);
	return answ;
}
int main()
{
	scanf("%d",&n);
	for (int i=1,x,y;i<n;i++)
	{
		scanf("%d%d",&x,&y);
		add(x,y);
		add(y,x);
	}
	for (int i=1;i<=n;i++)
	{
		scanf("%d",&w1[i]);
	}
	dfs1(1,1,1); dfs2(1,1);
	
	build(1,1,n);
/*	for (int i=1;i<=n;i++)
	{
		printf("%d ",id[i]);
	}
	printf("\n\n\n");*/
	int q;
	scanf("%d",&q);
	string s;
	int x,y;
//	printf("\n\n\n\n:qwq:: %d\n\n\n\n\n",querymax(1,1,n,2,4));
	while (q--)
	{
		cin>>s;
		scanf("%d%d",&x,&y);
		if (s[1]=='H')
		{
			
			change(1,1,n,id[x],y);
//			printf("：：：：：：：：：：：：%d \n",id[x]); 
			continue;
		}
		
		if (s[1]=='M')
		{//printf("qwq????\n");
			printf("%d\n",query_max(x,y));
			continue;
		}
		printf("%d\n",query_ans(x,y));
	}
	return 0;
}

自我吐槽：写完整\(leftson\)和\(rightson\)（似乎别人一般写ls/rs/lson/rson）的线段树，以及大片宏定义，加上毒瘤递归\(inline\)，这\(segment-tree\)码风可能永远改不掉了（写的很舒服）