【bzoj2836】魔法树 树链剖分+线段树

#include <cstdio>
#include <algorithm>
#define N 100010
#define lson l , mid , x << 1
#define rson mid + 1 , r , x << 1 | 1
using namespace std;
typedef long long ll;
int head[N] , to[N << 1] , next[N << 1] , cnt;
int fa[N] , deep[N] , si[N] , bl[N] , pos[N] , last[N] , tot , n;
ll sum[N << 2] , tag[N << 2];
char str[10];
void add(int x , int y)
{
	to[++cnt] = y , next[cnt] = head[x] , head[x] = cnt;
}
void dfs1(int x)
{
	int i;
	si[x] = 1;
	for(i = head[x] ; i ; i = next[i])
		if(to[i] != fa[x])
			fa[to[i]] = x , deep[to[i]] = deep[x] + 1 , dfs1(to[i]) , si[x] += si[to[i]];
}
void dfs2(int x , int c)
{
	int i , k = n;
	bl[x] = c , pos[x] = ++tot;
	for(i = head[x] ; i ; i = next[i])
		if(to[i] != fa[x] && si[k] < si[to[i]])
			k = to[i];
	if(k != n)
	{
		dfs2(k , c);
		for(i = head[x] ; i ; i = next[i])
			if(to[i] != fa[x] && to[i] != k)
				dfs2(to[i] , to[i]);
	}
	last[x] = tot;
}
void pushup(int x)
{
	sum[x] = sum[x << 1] + sum[x << 1 | 1];
}
void pushdown(int l , int r , int x)
{
	if(tag[x])
	{
		int mid = (l + r) >> 1;
		sum[x << 1] += tag[x] * (mid - l + 1) , tag[x << 1] += tag[x];
		sum[x << 1 | 1] += tag[x] * (r - mid) , tag[x << 1 | 1] += tag[x];
		tag[x] = 0;
	}
}
void update(int b , int e , ll a , int l , int r , int x)
{
	if(b <= l && r <= e)
	{
		sum[x] += a * (r - l + 1) , tag[x] += a;
		return;
	}
	pushdown(l , r , x);
	int mid = (l + r) >> 1;
	if(b <= mid) update(b , e , a , lson);
	if(e > mid) update(b , e , a , rson);
	pushup(x);
}
ll query(int b , int e , int l , int r , int x)
{
	if(b <= l && r <= e) return sum[x];
	pushdown(l , r , x);
	int mid = (l + r) >> 1;
	ll ans = 0;
	if(b <= mid) ans += query(b , e , lson);
	if(e > mid) ans += query(b , e , rson);
	return ans;
}
void solveupdate(int x , int y , ll a)
{
	while(bl[x] != bl[y])
	{
		if(deep[bl[x]] < deep[bl[y]]) swap(x , y);
		update(pos[bl[x]] , pos[x] , a , 1 , n , 1);
		x = fa[bl[x]];
	}
	if(deep[x] > deep[y]) swap(x , y);
	update(pos[x] , pos[y] , a , 1 , n , 1);
}
int main()
{
	int m , i , x , y;
	ll z;
	scanf("%d" , &n);
	for(i = 1 ; i < n ; i ++ ) scanf("%d%d" , &x , &y) , add(x , y) , add(y , x);
	fa[0] = -1 , dfs1(0) , dfs2(0 , 0);
	scanf("%d" , &m);
	while(m -- )
	{
		scanf("%s%d" , str , &x);
		if(str[0] == ‘Q‘) printf("%lld\n" , query(pos[x] , last[x] , 1 , n , 1));
		else scanf("%d%lld" , &y , &z) , solveupdate(x , y , z);
	}
	return 0;
}