rt,已看警钟。

https://www.luogu.com.cn/record/182007315

# include <bits/stdc++.h>

# define I return

# define AK 0

# define IOI ;

using namespace std;

typedef long long ll;

typedef pair <int, int> pii;

struct node {

	int x, w, id;

} ;

int n, mp[100005], s[100005], heavist[100005], x, y, tot, dfn[100005], maxx[400005], cover[400005], add[400005], a[100005], b[100005], k, st[100005], depth[100005], f[100005];

string op;

vector <node> v[100005];

void init1 (const int x, const int fa) {

	s[x] = 1, f[x] = fa;

	depth[x] = depth[fa] + 1;

	for (const node& i : v[x])
		if (i.x != fa) {

			b[i.x] = i.w, mp[i.id] = i.x;

			init1 (i.x, x);

			s[x] += s[i.x];

			if (s[heavist[x]] < s[i.x])
				heavist[x] = i.x;

		}

	return ;

}

void init2 (const int x, const int fa, const int s) {

	a[dfn[x] = ++ tot] = b[x], st[x] = s;

	if (! heavist[x])
		return ;

	init2 (heavist[x], x, s);

	for (const node& i : v[x])
		if (i.x != fa && i.x != heavist[x])
			init2 (i.x, x, i.x);

	return ;

}

void build (const int x, const int l, const int r) {

	cover[x] = -1;

	if (l == r) {

		maxx[x] = a[l];

		return ;

	}

	const int mid = l + r >> 1, left = x << 1, right = left | 1;

	build (left, l, mid), build (right, mid + 1, r);

	maxx[x] = max (maxx[left], maxx[right]);

	return ;

}

void pushdown (const int x, const int left, const int right) {

	if (~cover[x])
		maxx[left] = maxx[right] = cover[left] = cover[right] = cover[x], add[left] = add[right] = 0, cover[x] = -1;
	else if (add[x])
		maxx[left] += add[x], maxx[right] += add[x], add[left] += add[x], add[right] += add[x], add[x] = 0;

	return ;

}

void Cover (const int x, const int l, const int r, const int L, const int R) {

	if (l == L && r == R) {

		maxx[x] = cover[x] = k, add[x] = 0;

		return ;

	}

	const int mid = l + r >> 1, left = x << 1, right = left | 1;

	pushdown (x, left, right);

	if (R <= mid)
		Cover (left, l, mid, L, R);
	else if (L > mid)
		Cover (right, mid + 1, r, L, R);
	else
		Cover (left, l, mid, L, mid), Cover (right, mid + 1, r, mid + 1, R);

	maxx[x] = max (maxx[left], maxx[right]);

	return ;

}

void Add (const int x, const int l, const int r, const int L, const int R) {

	if (l == L && r == R) {

		maxx[x] += k;

		if (~cover[x])
			cover[x] += k;
		else
			add[x] += k;

		return ;

	}

	const int mid = l + r >> 1, left = x << 1, right = left | 1;

	pushdown (x, left, right);

	if (R <= mid)
		Add (left, l, mid, L, R);
	else if (L > mid)
		Add (right, mid + 1, r, L, R);
	else
		Add (left, l, mid, L, mid), Add (right, mid + 1, r, mid + 1, R);

	maxx[x] = max (maxx[left], maxx[right]);

	return ;

}

int find (const int x, const int l, const int r, const int L, const int R) {
//	cerr << L << '~' << R << ':' << x << ':' << l << '~' << r << '\n';
	if (l == L && r == R)
		return maxx[x];

	const int mid = l + r >> 1, left = x << 1, right = left | 1;

	pushdown (x, left, right);

	if (R <= mid)
		return find (left, l, mid, L, R);

	if (L > mid)
		return find (right, mid + 1, r, L, R);

	return max (find (left, l, mid, L, mid), find (right, mid + 1, r, mid + 1, R));

}

void Change (const int x) {

	Cover (1, 1, n, dfn[mp[x]], dfn[mp[x]]);

	return ;

}

void Cover (int x, int y) {

	while (st[x] ^ st[y]) {

		if (depth[st[x]] < depth[st[y]])
			swap (x, y);

		Cover (1, 1, n, dfn[st[x]], dfn[x]);

		x = f[st[x]];

	}

	if (dfn[x] > dfn[y])
		swap (x, y);

	if (dfn[x]^dfn[y])
		Cover (1, 1, n, dfn[x] + 1, dfn[y]);

	return ;

}

void Add (int x, int y) {

	while (st[x] ^ st[y]) {

		if (depth[st[x]] < depth[st[y]])
			swap (x, y);

		Add (1, 1, n, dfn[st[x]], dfn[x]);

		x = f[st[x]];

	}

	if (dfn[x] > dfn[y])
		swap (x, y);

	if (dfn[x]^dfn[y])
		Add (1, 1, n, dfn[x] + 1, dfn[y]);

	return ;

}

int Max (int x, int y) {

	int maxx = 0;

	while (st[x] ^ st[y]) {

		if (depth[st[x]] < depth[st[y]])
			swap (x, y);
//		cerr << x << '~' << y << ':' << st[x] << '~' << x << ':' << dfn[st[x]] << '~' << dfn[x] << '\n';
		maxx = max (maxx, find (1, 1, n, dfn[st[x]], dfn[x]));

		x = f[st[x]];

	}

	if (dfn[x] > dfn[y])
		swap (x, y);

	if (dfn[x]^dfn[y])
		maxx = max (maxx, find (1, 1, n, dfn[x] + 1, dfn[y]));

	return maxx;

}

int main () {

	ios::sync_with_stdio (0);

	cin.tie (0);

	cout.tie (0);

	cin >> n;

	for (int i = 1; i < n; ++ i)
		cin >> x >> y >> k, v[x].push_back ({y, k, i}), v[y].push_back ({x, k, i});

	init1 (1, 0), init2 (1, 0, 1);

	build (1, 1, n);

	while (cin >> op, op[0]^'S')
		if (op[0] == 'M') //cerr << "\n111\n",
			cin >> x >> y, cout << Max (x, y) << '\n';
		else if (op[0] == 'A')
			cin >> x >> y >> k, Add (x, y);
		else if (op[1] == 'h')
			cin >> x >> k, Change (x);
		else
			cin >> x >> y >> k, Cover (x, y);

	I AK IOI

}
/*
6
1 2 7
1 3 5
1 4 3
3 5 1
3 6 2
Ch 4 8
Ma 3 5
Ma 2 5
Co 2 5 10
Ma 2 4
Ma 2 6
Ma 3 6
Ma 5 6
Ad 1 4 51
Ma 5 4
Ma 1 5
Stop

8
8
10
10
2
10
54
10
*/