Wannfly day2 采蘑菇

这题简直树链剖分板子题。。。。真没啥可说的。当时不懂树剖，可惜啦

#include<cstring>                
#include<iostream>
#include<algorithm>
#include<queue>
using namespace std;
typedef long long ll;
const int maxn = 1e6 + 1000;
ll tree[4 * maxn];

int update(int node, int be, int en, int i, ll val) {
	int mid = be + en >> 1;
	int l = node * 2;
	int r = node * 2 + 1;

	if (be == en) {
		tree[node] += val;
		return 0;
	}

	if (i <= mid) update(l, be, mid, i, val);
	else  update(r, mid + 1, en, i, val);
	tree[node] = tree[l] + tree[r];
	return 0;
}
ll qurry(int node, int be, int en, int LL, int RR) {
	int mid = be + en >> 1;
	int l = node * 2;
	int r = node * 2 + 1;
	if (LL > en || RR < be) return 0;
	if (LL <= be && en <= RR) {
		return tree[node];
	}
	ll val1 = qurry(l, be, mid, LL, RR);
	ll val2 = qurry(r, mid + 1, en, LL, RR);
	return val1 + val2;
}
int n;
struct Node {
	int to;
	int next;
	ll len;
}G[2*maxn];

int cn = 0;
int head[maxn];
int add(int be, int en, ll len) {
	G[++cn].to = en;
	G[cn].len = len;
	G[cn].next = head[be];
	head[be] = cn;
	return 0;
}
int dep[maxn], son[maxn], siz[maxn], top[maxn];
int id[maxn],f[maxn];

int dfs(int x, int fa, int d) {
	dep[x] = d;
	f[x] = fa;
	siz[x] = 1;
	int s = 0;
	for (int i = head[x]; i; i = G[i].next) {
		int p = G[i].to;
		if (p == fa) continue;
		dfs(p, x, d + 1);

		siz[x] += siz[p];

		if (s < siz[p]) {
			s = siz[p];
			son[x] = p;
		}
	}
	return 0;
}
int cnt = 0;

int dfs2(int x, int t) {
	
	id[x] = ++cnt;
	top[x] = t;
	if (son[x]) dfs2(son[x], t);

	for (int i = head[x]; i; i = G[i].next) {
		int p = G[i].to;
		if (p == f[x] || p == son[x]) continue;
		dfs2(p, p);
	}
	return 0;
}


int main() {
	scanf("%d", &n);
	int be, en;
	ll len;
	for (int i = 1; i < n; i++) {
		scanf("%d %d %lld", &be, &en, &len);
		add(be, en, len);
		add(en, be, len);
	}
	
	dfs(1, -1, 0);
	dfs2(1, 1);
	int q;
	scanf("%d", &q);
	
	int x;
	int root = 1;
	ll ans = 0;
	ll cns = 0;
	ll sum = 0;
	ll a = 0;
	ll b = 0;
	while (q--) {
		int op;
		scanf("%d", &op);
		if (op == 1) {
			scanf("%d %lld", &x, &len);
			sum += len;
			update(1, 1, n, id[x], len);
			a = qurry(1, 1, n, id[root], id[root]);
			cns = 0;
			ans = 0;
			b = 0;
			for (int i = head[root]; i; i = G[i].next) {
				int p = G[i].to;
				ll ln = G[i].len;
				if (dep[p] > dep[root]) {
					ll c = qurry(1, 1, n, id[p], id[p] + siz[p] - 1);
					ans += ln * c;
					cns += c;
				}
				else {
					b = ln;
				}
			}
			
			ans += (sum - a - cns)*b;
			printf("%lld\n", ans);
		}
		else {
		
			scanf("%d", &x);
			root = x;
			a = qurry(1, 1, n, id[root], id[root]);
			cns = 0;
			ans = 0;
			b = 0;
			for (int i = head[root]; i; i = G[i].next) {
				int p = G[i].to;
				ll ln = G[i].len;
				if (dep[p] > dep[root]) {
					ll c = qurry(1, 1, n, id[p], id[p] + siz[p] - 1);
					ans += ln * c;
					cns += c;
				}
				else {
					b = ln;
				}
			}

			ans += (sum - a - cns)*b;
			printf("%lld\n", ans);
		}
	
	}
	return 0;
}