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\n", 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;

}