1036: [ZJOI2008]树的统计Count树链剖分

　　虽然是水题一枚，但是在我的不懈努下，交了80几发，在突然有一天重写的情况下，竟然1a了。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<map>
#include<vector>
#include<stdlib.h>
using namespace std;

const int maxn = 33333;
struct Node
{
    int next; int to;
}e[maxn*2];
int len, z;
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1

int head[maxn], top[maxn], son[maxn], father[maxn], size[maxn], deep[maxn], pos[maxn], val[maxn], vis[maxn];
int sum[maxn<<2],Max[maxn<<2];

void add(int from, int to)
{
    e[len].to = to;
    e[len].next = head[from];
    head[from] = len++;
}

void init(int x)
{
    size[x] = 1; son[x] = 0;
    for (int i = head[x]; ~i; i = e[i].next){
        int cc = e[i].to;
        if (cc == father[x]) continue;
        deep[cc] = deep[x] + 1; father[cc] = x;
        init(cc);
        size[x] += size[cc];
        if (size[son[x]] < size[cc]) son[x] = cc;
    }
}

void dfs(int x, int tp)
{
    pos[x] = ++z; vis[z] = x; top[x] = tp;
    if(son[x]) dfs(son[x],tp);
    for (int i = head[x]; i != -1; i = e[i].next){
        int cc = e[i].to;
        if (cc == father[x] || cc == son[x]) continue;
        dfs(cc, cc);
    }
}

void up(int rt)
{
    sum[rt] = sum[rt << 1] + sum[rt << 1 | 1];
    Max[rt] = max(Max[rt << 1], Max[rt << 1 | 1]);
}
void build(int l, int r, int rt)
{
    if (l == r){
        Max[rt] = sum[rt] = val[vis[l]]; return;
    }
    int mid = (l + r) >> 1;
    build(lson);
    build(rson);
    up(rt);
}

void update(int key, int ans, int l, int r, int rt)
{
    if (l == r){
        Max[rt] = sum[rt] = ans; return;
    }
    int mid = (l + r) >> 1;
    if (key <= mid) update(key, ans, lson);
    else update(key, ans, rson);
    up(rt);
}

int ask_max(int L, int R, int l, int r, int rt)
{
    if (L <= l&&r <= R) return Max[rt];
    int ans = -1e9;
    int mid = (l + r) >> 1;
    if (L <= mid) ans = max(ans, ask_max(L, R, lson));
    if (R > mid) ans = max(ans, ask_max(L, R, rson));
    return ans;
}

int ask_sum(int L, int R, int l, int r, int rt)
{
    if (L <= l&&r <= R) return sum[rt];
    int ans = 0;
    int mid = (l + r) >> 1;
    if (L <= mid) ans += ask_sum(L, R, lson);
    if (R > mid) ans += ask_sum(L, R, rson);
    return ans;
}

void gao_max(int x, int y)
{
    int ans = -1e9;
    int fx = top[x]; int fy = top[y];
    while (fx != fy){
        if (deep[fx] < deep[fy]){
            swap(x, y); swap(fx, fy);
        }
        ans = max(ans, ask_max(pos[fx], pos[x], 1, z, 1));
        x = father[fx]; fx = top[x];
    }
    if (deep[x]>deep[y]){
        swap(x, y);
    }
    ans = max(ans, ask_max(pos[x], pos[y], 1, z, 1));
    printf("%d
", ans);
}

void gao_sum(int x, int y)
{
    int ans = 0;
    int fx = top[x]; int fy = top[y];
    while (fx != fy){
        if (deep[fx] < deep[fy]){
            swap(x, y); swap(fx, fy);
        }
        ans += ask_sum(pos[fx], pos[x], 1, z, 1);
        x = father[fx]; fx = top[x];
    }
    if (deep[x]>deep[y]) swap(x, y);
    ans += ask_sum(pos[x], pos[y], 1, z, 1);
    printf("%d
", ans);
}


int main()
{
    int n;
    int a, b, c;
    int q;
    char str[1000];
    while (cin >> n){
        len = z = 0;
        memset(head, -1, sizeof(head));
        for (int i = 0; i < n - 1; i++){
            cin >> a >> b; add(a, b); add(b, a);
        }
        for (int i = 1; i <= n; i++){
            scanf("%d", &val[i]);
        }
        init(1); dfs(1, 1); build(1, z, 1);
        cin >> q;
        while (q--){
            scanf("%s%d%d", str, &a, &b);
            if (strcmp(str, "QMAX") == 0){
                gao_max(a, b);
            }
            else if (strcmp(str, "QSUM") == 0){
                gao_sum(a, b);
            }
            else update(pos[a], b, 1, z, 1);
        }
    }
    return 0;
}