【luogu P3178 [HAOI2015]树上操作】 题解

题目链接：https://www.luogu.org/problemnew/show/P3178
模板题 菜

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#define lson left, mid, rt<<1
#define rson mid + 1, right, rt<<1|1
#define ll long long
using namespace std;
const int maxn = 200000 + 10;
ll n, m, root, mod;
ll node[maxn], num; 
ll fa[maxn], dep[maxn], size[maxn], son[maxn], top[maxn], seg[maxn], rev[maxn];
ll res;
struct edge{
	ll from, to, next;	
}e[maxn<<2];
ll head[maxn], cnt;
//-------------------------------------------------------
ll tree[maxn<<2], lazy[maxn<<2];
void PushUP(ll rt)
{
	tree[rt] = (tree[rt<<1] + tree[rt<<1|1]);
}
void build(ll left, ll right, ll rt)
{
	if(left == right)
	{
		tree[rt] = rev[left];
		tree[rt] = tree[rt];
		return;
	}
	ll mid = (left + right) >> 1;
	build(lson);
	build(rson);
	PushUP(rt);
}
void PushDOWN(ll left, ll right, ll rt, ll mid)
{
	lazy[rt<<1] += lazy[rt]; 
	lazy[rt<<1|1] += lazy[rt];
	tree[rt<<1] += (mid - left + 1)*lazy[rt];
	tree[rt<<1|1] += (right - mid)*lazy[rt];
	lazy[rt] = 0;
}
ll query(ll l, ll r, ll left, ll right, ll rt)
{
	ll res = 0;
	if(l <= left && r >= right)
	{
		return tree[rt];
	}
	ll mid = (left + right)>>1;
	if(lazy[rt]) PushDOWN(left, right, rt, mid);
	if(l <= mid) res += query(l, r, lson);
	if(r > mid) res += query(l, r, rson);
	return res;
}
void update(ll l, ll r, ll add, ll left, ll right, ll rt)
{
	if(l <= left && r >= right)
	{
		lazy[rt] += add;
		tree[rt] += (right - left + 1)*add;
		return;
	}
	ll mid = (left + right)>>1;
	PushDOWN(left, right, rt, mid);
	if(l <= mid) update(l, r, add, lson);
	if(r > mid) update(l, r, add, rson);
	PushUP(rt);
}
//------------------------------------------------
void add(ll u, ll v)
{
	e[++cnt].from = u;
	e[cnt].next = head[u];
	e[cnt].to = v;
	head[u] = cnt;
}
void dfs1(ll u, ll f, ll d)
{
	ll maxson = -1;
	size[u] = 1;
	fa[u] = f;
	dep[u] = d;
	for(ll i = head[u]; i != -1; i = e[i].next)
	{
		ll v = e[i].to;
		if(v != f)
		{
			dfs1(v, u, d + 1);
			size[u] += size[v];
			if(size[v] > maxson) son[u] = v, maxson = size[v];
		}
	}
}
void dfs2(ll u, ll t)
{
	seg[u] = ++num;
	rev[num] = node[u];
	top[u] = t;
	if(!son[u]) return;
	dfs2(son[u], t);
	for(ll i = head[u]; i != -1; i = e[i].next)
	{
		ll v = e[i].to;
		if(fa[u] == v || son[u] == v) continue;
		dfs2(v, v);
	}
}
ll qRange(ll x, ll y)
{
	ll ans = 0;
	while(top[x] != top[y])
	{
		if(dep[top[x]] < dep[top[y]]) swap(x, y);
		res = 0;
		res = query(seg[top[x]], seg[x], 1, n, 1);
		ans = ans + res;
		x = fa[top[x]];
	}
	if(dep[x] > dep[y]) swap(x, y);
	res = 0;
	res = query(seg[x], seg[y], 1, n, 1);
	ans = ans + res;
	return ans;
}
void updRange(ll x, ll y, ll k)
{
	while(top[x] != top[y])
	{
		if(dep[top[x]] < dep[top[y]]) swap(x, y);
		update(seg[top[x]], seg[x], k, 1, n, 1);
		x = fa[top[x]];
	}
	if(dep[x] > dep[y]) swap(x, y);
	update(seg[x], seg[y], k, 1, n, 1);
}
ll qSon(ll x)
{
	res = 0;
	res = query(seg[x], seg[x]+size[x]-1, 1, n, 1);
	return res;
}
ll updSon(ll x, ll k)
{
	update(seg[x], seg[x]+size[x]-1, k, 1, n, 1);
}
int main()
{
	memset(head, -1, sizeof(head));
	scanf("%lld%lld",&n,&m);
	root = 1;
	for(ll i = 1; i <= n; i++)
	scanf("%lld",&node[i]);
	for(ll i = 1; i < n; i++)
	{
		ll u, v;
		scanf("%lld%lld",&u,&v);
		add(u, v), add(v, u);
	}
	dfs1(root, 0, 1);
	dfs2(root, root);
	build(1,n,1);
	for(ll i = 1; i <= m; i++)
	{
		ll opt, x, y, z;
		scanf("%lld",&opt);
		if(opt == 1)
		{
			scanf("%lld%lld%",&x,&y);
			updRange(x, x, y);
		}
		if(opt == 2)
		{
			scanf("%lld%lld",&x,&y);
			updSon(x, y);
		}
		if(opt == 3)
		{
			scanf("%lld",&x);
			printf("%lld\n",qRange(x, 1));
		}
	}
	return 0;
}