洛谷 P2590 [ZJOI2008]树的统计

题链

树链剖分模板题，注意ai数据范围就好

//#include <bits/stdc++.h>
#include <iostream>
#include <vector>
using namespace std;
#define ls rt<<1
#define rs rt<<1|1
#define LL long long
#define PI acos(-1.0)
#define eps 1e-8
#define Pair pair<double,double>
// notice
#define mod 998244353 
#define MAXN 2e6
#define MS 30009

LL n,m;
LL a[MS];
vector<LL > vc[MS];
LL sz[MS];
LL fa[MS];
LL dep[MS];
LL zson[MS];
LL tot;
LL dfn[MS];
LL top[MS];
LL w[MS];
struct node{
	LL maxn,val;
}p[MS<<2];

void dfs1(LL x,LL f){
	sz[x] = 1;
	fa[x] = f;
	dep[x] = dep[f]+1;
	int maxzson = 0;
	for(auto &i:vc[x]){
		if(i != f){
			dfs1(i,x);
			sz[x] += sz[i];
			if(sz[i] >= maxzson){
				maxzson = sz[i];
				zson[x] = i;
			}
		} 
	}
}

void dfs2(LL x,LL tp){
	dfn[x] = ++tot;
	top[x] = tp;
	w[tot] = a[x];
	if(zson[x]) dfs2(zson[x],tp);
	for(auto &i:vc[x]){
		if(i != zson[x] && i != fa[x]){
			dfs2(i,i);
		}
	}
}

void push_up(int rt){
	p[rt].val = p[ls].val + p[rs].val;
	p[rt].maxn = max(p[ls].maxn,p[rs].maxn);
}

void build(int l,int r,int rt){
	if(l == r){
		p[rt] = {w[l],w[l]};
		return;
	}
	int m = l+r>>1;
	build(l,m,ls);
	build(m+1,r,rs);
	push_up(rt);
}

void update(int pos,int l,int r,int rt,LL val){
	if(l == r){
		p[rt] = {val,val};
		return;
	}
	int m = l+r>>1;
	if(m >= pos) update(pos,l,m,ls,val);
	else update(pos,m+1,r,rs,val);
	push_up(rt);
}

node query(int L,int R,int l,int r,int rt){
	if(L <= l && r <= R){
		return p[rt];
	}
	int m = l+r>>1;
	if(m < L) return query(L,R,m+1,r,rs);
	else if(m >= R) return query(L,R,l,m,ls);
	else{
		node t1 = query(L,R,l,m,ls);
		node t2 = query(L,R,m+1,r,rs);
		node ans;
		ans.val = t1.val + t2.val;
		ans.maxn = max(t1.maxn,t2.maxn);
		return ans; 
	}
}

node op23(LL x,LL y){
	node ans = {-(LL)MAXN,0};
	while(top[x] != top[y]){
		if(dep[ top[x] ] < dep[ top[y] ]) swap(x,y);
		node cc = query(dfn[top[x]],dfn[x],1,n,1);
		ans.val += cc.val;
		ans.maxn = max(ans.maxn,cc.maxn); 
		x = fa[top[x]];
	}
	if(dep[x] > dep[y]) swap(x,y);
	node cc = query(dfn[x],dfn[y],1,n,1);
	ans.val += cc.val;
	ans.maxn = max(ans.maxn,cc.maxn);
	return ans;
}

void change(LL pos,LL val){
	update(dfn[pos],1,n,1,val);
}

int main() {
	ios::sync_with_stdio(false);
	cin >> n;
	for(int i=2;i<=n;i++){
		LL u,v;
		cin >> u >> v;
		vc[u].push_back(v);
		vc[v].push_back(u);
	}
	for(int i=1;i<=n;i++){
		cin >> a[i];
	}
	dfs1(1,1);
	dfs2(1,1);
	build(1,n,1);
	cin >> m;
	while(m--){
		char s[10];
		LL x,y;
		cin >> s >> x >> y;
		if(s[0] == 'Q'){
			node ans = op23(x,y);
			if(s[1] == 'M') cout << ans.maxn << "\n";
			else if(s[1] == 'S') cout << ans.val << "\n";
		}
		else if(s[0] == 'C'){
			change(x,y);
		}
	}
	

	return 0;
}