RT，我初始化的数应该比最小的权值还小吧。。。

#include<bits/stdc++.h>

#define ls(k) k << 1
#define rs(k) k << 1 | 1

using namespace std;

const int N = 3e4 + 10;

void read(int &x)
{
	x = 0;
	register char s = getchar();
	while(s < '0' || s > '9'){s = getchar();}
	while(s >= '0' && s <= '9'){x = (x << 3) + (x << 1) + (s ^ 48); s = getchar();}
}

struct EDGE{
	int to, next;
}edge[N << 1];
int head[N], num = 0;
void add(int x, int y)
{
	edge[++num].next = head[x];
	edge[num].to = y;
	head[x] = num;
}

struct TREE{
	int sum;
	int max;
}tree[N << 2];
int tag[N << 2];

int top[N], size[N], fa[N], son[N], dep[N], rev[N], seg[N];

int n, val[N];

void dfs1(int u, int f)
{
	fa[u] = f;
	dep[u] = dep[f] + 1;
	size[u] = 1;
	for(int i = head[u]; i; i = edge[i].next)
	{
		int v = edge[i].to;
		if(v == f)
			continue;
		dfs1(v, u);
		size[u] += size[v];
		if(size[v] > size[son[u]])
			son[u] = v;
	}
}

void dfs2(int u, int t)
{
	top[u] = t;
	seg[u] = ++seg[0];
	rev[seg[0]] = u;
	if(son[u])
		dfs2(son[u], t);	
	for(int i = head[u]; i; i = edge[i].next)
	{
		int v = edge[i].to;
		if(v == son[u] || v == fa[u])
			continue;
		dfs2(v, v);
	}
}

void update(int k)
{
	tree[k].max = max(tree[ls(k)].max, tree[rs(k)].max);
	tree[k].sum = tree[ls(k)].sum + tree[rs(k)].sum;
}

void build(int k, int l, int r)
{
	tree[k].sum = 0;
	tree[k].max = -0x3f3f3f;
	if(l == r)
	{
		tree[k].max = val[rev[l]];
		tree[k].sum = val[rev[l]];
		return;
	}
	int mid = (l + r) >>1;
	build(ls(k), l, mid);
	build(rs(k), mid + 1, r);
	update(k);
}

void modify(int k, int l, int r, int x, int v)
{
	if(l == r && l == x)
	{
		tree[k].max = v;
		tree[k].sum = v;
		return;
	}
	int mid = (l + r) >> 1;
	if(x <= mid)
		modify(ls(k), l, mid, x, v);
	else
		modify(rs(k), mid + 1, r, x, v);
	update(k);
}

int query(int k, int l, int r, int x, int y, bool op)
{
	if(x <= l && r <= y)
	{
		if(op)
			return tree[k].max;
		else
			return tree[k].sum; 
	}
	int mid = (l + r) >> 1;
	int ans = 0;
	int maxx = -0x3f3f3f;
	if(x <= mid)
	{
		if(op)
			maxx = max(maxx, query(ls(k), l, mid, x, y, op));
		else
			ans += query(ls(k), l, mid, x, y, op);
	}
	if(y > mid)
	{
		if(op)
			maxx = max(maxx, query(rs(k), mid + 1, r, x, y, op));
		else
			ans += query(rs(k), mid + 1, r, x, y, op);
	}
	if(op)
		return maxx;
	return ans;
}

int ask(int x, int y, bool op)
{
	int ans = 0;
	int maxx = -0x3f3f3f;
	while(top[x] != top[y])
	{
		if(dep[top[x]] < dep[top[y]])
			swap(x, y);
		if(op)
			maxx = max(maxx, query(1, 1, seg[0], seg[x], seg[top[x]], op));
		else
			ans += query(1, 1, seg[0], seg[x], seg[top[x]], op);
		x = fa[top[x]];
	}
	if(seg[x] > seg[y])
		swap(x, y);
	if(op)
		maxx = max(maxx, query(1, 1, seg[0], seg[x], seg[y], op));
	else
		ans += query(1, 1, seg[0], seg[x], seg[y], op);
	if(op)
		return maxx;
	return ans;
}

int main()
{
	read(n);
	for(int i = 1; i <= n - 1; i++)
	{
		int x, y;
		read(x);read(y);
		add(x, y);
		add(y, x);
	}
	for(int i = 1; i <= n; i++)
		cin >> val[i];
	dfs1(1, 0);
	seg[0] = 0;
	dfs2(1, 1);
	build(1, 1, seg[0]);
	int q;
	read(q);
	while(q--)
	{
		char s[6];
		scanf("%s", s + 1);
		if(s[2] == 'M')
		{
			int u, v;
			read(u);read(v);
			int ans = ask(u, v, 1);
			cout << ans << endl;
		}
		else if(s[2] == 'S')
		{
			int u, v;
			read(u);read(v);
			int ans = ask(u, v, 0);
			cout << ans << endl;
		}
		else
		{
			int u, t;
			read(u);read(t);
			modify(1, 1, seg[0], seg[u], t);
		}
	}
	return 0;
}