luogu2590 [ZJOI2008]树的统计

树剖裸题

#include <iostream>
#include <cstdio>
using namespace std;
int n, uu, vv, hea[30005], ecnt, w[30005], ww[30005], dep[30005], cnt;
int idx[30005], son[30005], fa[30005], top[30005], q, wt[30005], siz[30005];
char ss[15];
struct Edge{
	int too, nxt;
}edge[60005];
void add_edge(int fro, int too){
	edge[++ecnt].nxt = hea[fro];
	edge[ecnt].too = too;
	hea[fro] = ecnt;
}
struct SGT{
	int sum[120005];
	int zdz[120005];
	void build(int o, int l, int r){
		if(l==r)	zdz[o] = sum[o] = wt[l];
		else{
			int mid=(l+r)>>1;
			int lson=o<<1;
			int rson=lson|1;
			zdz[lson] = zdz[rson] = -0x3f3f3f3f;
			if(l<=mid)	build(lson, l, mid);
			if(mid<r)	build(rson, mid+1, r);
			sum[o] = sum[lson] + sum[rson];
			zdz[o] = max(zdz[lson], zdz[rson]);
		}
	}
	void change(int o, int l, int r, int x, int k){
		if(l>=x && r<=x) sum[o] = zdz[o] = k;
		else{
			int mid=(l+r)>>1;
			int lson=o<<1;
			int rson=lson|1;
			if(x<=mid)	change(lson, l, mid, x, k);
			if(mid<x)	change(rson, mid+1, r, x, k);
			sum[o] = sum[lson] + sum[rson];
			zdz[o] = max(zdz[lson], zdz[rson]);
		}
	}
	int querySum(int o, int l, int r, int x, int y){
		if(l>=x && r<=y)	return sum[o];
		else{
			int mid=(l+r)>>1;
			int lson=o<<1;
			int rson=lson|1;
			int ans=0;
			if(x<=mid)	ans += querySum(lson, l, mid, x, y);
			if(mid<y)	ans += querySum(rson, mid+1, r, x, y);
			return ans;
		}
	}
	int queryZdz(int o, int l, int r, int x, int y){
		if(l>=x && r<=y)	return zdz[o];
		else{
			int mid=(l+r)>>1;
			int lson=o<<1;
			int rson=lson|1;
			int ans=-0x3f3f3f3f;
			if(x<=mid)	ans = max(ans, queryZdz(lson, l, mid, x, y));
			if(mid<y)	ans = max(ans, queryZdz(rson, mid+1, r, x, y));
			return ans;
		}
	}
}sgt;
void dfs1(int x, int f){
	fa[x] = f;
	dep[x] = dep[f] + 1;
	siz[x] = 1;
	int maxSon=-1;
	for(int i=hea[x]; i; i=edge[i].nxt){
		int t=edge[i].too;
		if(t==f)	continue;
		dfs1(t, x);
		siz[x] += siz[t];
		if(maxSon<siz[t]){
			maxSon = siz[t];
			son[x] = t;
		}
	}
}
void dfs2(int x, int topf){
	top[x] = topf;
	idx[x] = ++cnt;
	wt[cnt] = w[x];
	if(!son[x])	return ;
	dfs2(son[x], topf);
	for(int i=hea[x]; i; i=edge[i].nxt){
		int t=edge[i].too;
		if(t==fa[x] || t==son[x])	continue;
		dfs2(t, t);
	}
}
int queryRangeSum(int uu, int vv){
	int ans=0;
	while(top[uu]!=top[vv]){
		if(dep[top[uu]]<dep[top[vv]])	swap(uu, vv);
		ans += sgt.querySum(1, 1, n, idx[top[uu]], idx[uu]);
		uu = fa[top[uu]];
	}
	if(dep[uu]>dep[vv])	swap(uu, vv);
	ans += sgt.querySum(1, 1, n, idx[uu], idx[vv]);
	return ans;
}
int queryRangeZdz(int uu, int vv){
	int ans=-0x3f3f3f3f;
	while(top[uu]!=top[vv]){
		if(dep[top[uu]]<dep[top[vv]])	swap(uu, vv);
		ans = max(ans, sgt.queryZdz(1, 1, n, idx[top[uu]], idx[uu]));
		uu = fa[top[uu]];
	}
	if(dep[uu]>dep[vv])	swap(uu, vv);
	ans = max(ans, sgt.queryZdz(1, 1, n, idx[uu], idx[vv]));
	return ans;
}
int main(){
	cin>>n;
	for(int i=1; i<n; i++){
		scanf("%d %d", &uu, &vv);
		add_edge(uu, vv);
		add_edge(vv, uu);
	}
	for(int i=1; i<=n; i++)
		scanf("%d", &w[i]);
	dep[1] = 1;
	dfs1(1, 0);
	dfs2(1, 1);
	sgt.build(1, 1, n);
	cin>>q;
	while(q--){
		scanf("%s %d %d", ss, &uu, &vv);
		if(ss[1]=='H')	sgt.change(1, 1, n, idx[uu], vv);
		if(ss[1]=='M')	printf("%d
", queryRangeZdz(uu, vv));
		if(ss[1]=='S')	printf("%d
", queryRangeSum(uu, vv));
	}
	return 0;
}