Hdu3966( Aragorn's Story ) 树链剖分

点更新树链剖分入门题，诶 错了好多发，提到同一点时没更新，边数组开小了一倍。

#include <cstdio>
#include <algorithm>
#include <iostream>
#include <string.h>
using namespace std;
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
const int maxn = 55555;
int head[maxn];
int top[maxn];
struct Node
{
    int to; int next;
}e[maxn * 2];
int father[maxn];
int deep[maxn];
int size[maxn];
int son[maxn];
int pos[maxn];
int color[maxn << 2];
int vis[maxn];
int len, z;
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 != -1; i = e[i].next){
        int cc = e[i].to;
        if (cc == father[x]) continue;
        father[cc] = x; deep[cc] = deep[x] + 1;
        init(cc);
        size[x] += size[cc];
        if (size[cc] > size[son[x]]) son[x] = cc;
    }
}

void dfs(int x, int tp)
{
    pos[x] = ++z; 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 down(int rt)
{
    if (color[rt]){
        color[rt << 1] += color[rt];
        color[rt << 1 | 1] += color[rt];
        color[rt] = 0;
    }
}

void update(int L, int R, int ans, int l, int r, int rt)
{
    if (L <= l&&r <= R){
        color[rt] += ans; return;
    }
    int mid = (l + r) >> 1;
    down(rt);
    if (L <= mid) update(L, R, ans, lson);
    if (R > mid) update(L, R, ans, rson);
}

int ask(int key, int l, int r, int rt)
{
    if (l == r) return color[rt];
    down(rt);
    int mid = (l + r) >> 1;
    if (key <= mid) return ask(key, lson);
    else return ask(key, rson);
}

void gao(int x, int y, int ans)
{
    int f1 = top[x]; int f2 = top[y];
    while (f1 != f2){
        if (deep[f1] < deep[f2]){
            swap(f1, f2); swap(x, y);
        }
        update(pos[f1], pos[x], ans, 1, z, 1);
        x = father[f1]; f1 = top[x];
    }
    if (deep[x]>deep[y]){
        swap(x, y);
    }
    update(pos[x], pos[y], ans, 1, z, 1);
}

int main()
{
    int n, m, k;
    int a, b, c;
    char str[100];
    while (cin >> n >> m >> k){
        memset(head, -1, sizeof(head));
        memset(color, 0, sizeof(color));
        memset(size, 0, sizeof(size));
        deep[1] = 1;
        len = 0; z = 0;
        for (int i = 1; i <= n; i++){
            scanf("%d", &vis[i]);
        }
        for (int i = 0; i < m; i++){
            scanf("%d%d", &a, &b);
            add(a, b); add(b, a);
        }
        init(1); dfs(1, 1);
        for (int i = 0; i < k; i++){
            scanf("%s", str);
            if (str[0] == 'Q'){
                scanf("%d", &a);
                printf("%d
", vis[a] + ask(pos[a], 1, z, 1));
            }
            if (str[0] == 'I'){
                scanf("%d%d%d", &a, &b, &c);
                gao(a, b, c);
            }
            if (str[0] == 'D'){
                scanf("%d%d%d", &a, &b, &c);
                gao(a, b, -c);
            }
        }
    }
    return 0;
}