Luogu P3833 [SHOI2012]魔法樹

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <complex>
#include <algorithm>
#include <climits>
#include <queue>
#include <map>
#include <set>
#include <vector>
#include <iomanip>
#define
#define

using namespace std;
typedef long long ll;
int n, m, cnt, a, b, q; ll c;
int fa[A], dfn[A], siz[A], dep[A], top[A], son[A];
namespace Seg {
    struct node {
        int l, r; ll w, f;
    }tree[A << 2];
    void build(int k, int l, int r) {
        tree[k].l = l; tree[k].r = r;
        if (l == r) {
            tree[k].w = 0;
            return;
        }
        int m = (l + r) >> 1;
        build(k << 1, l, m);
        build(k << 1 | 1, m + 1, r);
    }
    void down(int k) {
        tree[k << 1].f += tree[k].f;
        tree[k << 1 | 1].f += tree[k].f;
        tree[k << 1].w += (tree[k << 1].r - tree[k << 1].l + 1) * tree[k].f;
        tree[k << 1 | 1].w += (tree[k << 1 | 1].r - tree[k << 1 | 1].l + 1) * tree[k].f;
        tree[k].f = 0;
    }
    void change(int k, int l, int r, ll add) {
        if (tree[k].l >= l and tree[k].r <= r) {
            tree[k].w += (tree[k].r - tree[k].l + 1) * add;
            tree[k].f += add;
            return;
        }
        if (tree[k].f) down(k);
        int m = (tree[k].l + tree[k].r) >> 1;
        if (l <= m) change(k << 1, l, r, add);
        if (r > m) change(k << 1 | 1, l, r, add);
        tree[k].w = tree[k << 1].w + tree[k << 1 | 1].w;
    }
    ll ask(int k, int l, int r) {
        if (tree[k].l >= l and tree[k].r <= r) return tree[k].w;
        if (tree[k].f) down(k);
        int m = (tree[k].l + tree[k].r) >> 1; ll ans = 0;
        if (l <= m) ans += ask(k << 1, l, r);
        if (r > m) ans += ask(k << 1 | 1, l, r);
        return ans;
    }
}
namespace Cut {
    struct node {
        int next, to;
    }e[A];
    int head[A], num;
    void add(int fr, int to) {
        e[++num].next = head[fr];
        e[num].to = to;
        head[fr] = num;
    }
    void prepare(int fr) {
        siz[fr] = 1;
        for (int i = head[fr]; i; i = e[i].next) {
            int ca = e[i].to;
            if (ca == fa[fr]) continue;
            fa[ca] = fr;
            dep[ca] = dep[fr] + 1;
            prepare(ca);
            siz[fr] += siz[ca];
            if (siz[ca] > siz[son[fr]]) son[fr] = ca;
        }
    }
    void dfs(int fr, int tp) {
        dfn[fr] = ++cnt, top[fr] = tp;
        if (!son[fr]) return;
        dfs(son[fr], tp);
        for (int i = head[fr]; i; i = e[i].next) {
            int ca = e[i].to;
            if (ca == fa[fr] or ca == son[fr]) continue;
            dfs(ca, ca);
        }
    }
    void change(int x, int y, ll val) {
        while (top[x] != top[y]) {
            if (dep[top[x]] < dep[top[y]]) swap(x, y);
            Seg::change(1, dfn[top[x]], dfn[x], val);
            x = fa[top[x]];
        }
        if (dep[x] > dep[y]) swap(x, y);
        Seg::change(1, dfn[x], dfn[y], val);
    }
    ll ask(int a) {
        return Seg::ask(1, dfn[a], dfn[a] + siz[a] - 1);
    }
}


int main(int argc, char const *argv[]) {
    scanf("%d", &n);
    for (int i = 2; i <= n; i++) {
        scanf("%d%d", &a, &b); a++; b++;
        Cut::add(a, b);
    }
    Cut::prepare(1); Cut::dfs(1, 1);
    Seg::build(1, 1, n);
    scanf("%d", &q);
    while (q--) {
        char opt = getchar();
        if (opt == 'A') {
            scanf("%d%d%lld", &a, &b, &c); a++; b++;
            Cut::change(a, b, c);
        }
        else {
            scanf("%d", &a); a++;
            printf("%lld\n", Cut::ask(a));
        }
    }
}