bzoj1036 [ZJOI2008]树的统计Count

题目

　　bzoj1036

 

代码

#include <bits/stdc++.h>
using namespace std;
const int N = 100005;
const int inf = 1e9;

inline int read()
{
	int x = 0, f = 1; char ch = getchar();
	while (ch < '0' || ch > '9') {if (ch == '-') f = -1; ch = getchar();}
	while (ch >= '0' && ch <= '9') {x = x * 10 + ch - '0'; ch = getchar();}
	return x * f;
}

int n, Q, w[N];
vector<int> to[N];

int fa[N], deep[N], sz[N], son[N];
void dfs1(int x)
{
	sz[x] = 1;
	for(int i = 0; i < to[x].size(); i++)
	{
		int k = to[x][i];
		if(k == fa[x]) continue;
		fa[k] = x; deep[k] = deep[x] + 1;
		dfs1(k); sz[x] += sz[k];
		if(sz[k] > sz[son[x]]) son[x] = k;
	}
}

int tot, id[N], dfn[N], top[N];
void dfs2(int x, int tp)
{
	dfn[x] = ++tot; id[tot] = x; top[x] = tp;
	if(son[x]) dfs2(son[x], tp);
	for(int i = 0; i < to[x].size(); i++)
	{
		int k = to[x][i];
		if(k != fa[x] && k != son[x]) dfs2(k, k);		
	}
}

struct node
{
	int l, r, sum, mx;
}T[N << 3];

void pushup(int p)
{
	T[p].sum = T[p << 1].sum + T[p << 1 | 1].sum;
	T[p].mx = max(T[p << 1].mx, T[p << 1 | 1].mx);
}

void build(int p, int x, int y)
{
	T[p].l = x; T[p].r = y;
	if(x == y) {T[p].sum = T[p].mx = w[id[x]]; return;}
	int mid = (x + y) >> 1;
	build(p << 1, x, mid); build(p << 1 | 1, mid + 1, y);
	pushup(p);
}

void change(int p, int x, int v)
{
	int pl = T[p].l, pr = T[p].r;
	if(pl == x && pr == x)
	{
		T[p].sum = T[p].mx = v;
		return;
	}
	int mid = (pl + pr) >> 1;
	if(x <= mid) change(p << 1, x, v);
	else change(p << 1 | 1, x, v);
	pushup(p);
}

int query_max(int p, int x, int y)
{
	int pl = T[p].l, pr = T[p].r;
	if(pl == x && pr == y) return T[p].mx;
	int mid = (pl + pr) >> 1;
	if(y <= mid) return query_max(p << 1, x, y);
	else if(x > mid) return query_max(p << 1 | 1, x, y);
	else return max(query_max(p << 1, x, mid), query_max(p << 1 | 1, mid + 1, y));
}

int query_sum(int p, int x, int y)
{
	int pl = T[p].l, pr = T[p].r;
	if(pl == x && pr == y) return T[p].sum;
	int mid = (pl + pr) >> 1;
	if(y <= mid) return query_sum(p << 1, x, y);
	else if(x > mid) return query_sum(p << 1 | 1, x, y); 
	return query_sum(p << 1, x, mid) + query_sum(p << 1 | 1, mid + 1, y);
}

int QMAX(int x, int y)
{
	int cnt = -inf;
	while(top[x] != top[y])
	{
		if(deep[top[x]] < deep[top[y]]) swap(x, y);
		cnt = max(cnt, query_max(1, dfn[top[x]], dfn[x]));
		x = fa[top[x]];
	}
	if(deep[x] < deep[y]) swap(x, y);
	cnt = max(cnt, query_max(1, dfn[y], dfn[x]));
	return cnt;
}

int QSUM(int x, int y)
{
	int cnt = 0;
	while(top[x] != top[y])
	{
		if(deep[top[x]] < deep[top[y]]) swap(x, y);
		cnt += query_sum(1, dfn[top[x]], dfn[x]);
		x = fa[top[x]];
	}
	if(deep[x] < deep[y]) swap(x, y);
	cnt += query_sum(1, dfn[y], dfn[x]);
	return cnt;
}

int main()
{	
	n = read();
	for(int i = 1; i < n; i++)
	{
		int x = read(), y = read();
		to[x].push_back(y); to[y].push_back(x);
	}
	for(int i = 1; i <= n; i++) w[i] = read();
	dfs1(1);
	dfs2(1, 0);
	build(1, 1, n);
	Q = read();
	while(Q--)
	{
		char op[10]; scanf("%s", op);
		int x = read(), y = read();
		if(op[0] == 'C') change(1, dfn[x], y);
		else if(op[1] == 'M') printf("%d\n", QMAX(x, y));
		else printf("%d\n", QSUM(x, y));
	}
	return 0;
}