Solution

这是一题树链剖分的模板题,接着这个题目我仔仔细细重新在OI Wiki学了一下之前一直不是很懂的树链剖分总算是搞定了,以前只会把一棵树控制的全部子树转化到线性的可执行区间,然后再去树状数组操作之类的,并没有把重子节点这些名次好好理解,现在看了之后还是有了比较深刻的理解,过几个简单变形题应该是没问题了,这里主要分享下写的线段树和两次处理的码风把感觉还是挺好的。

然后就再聊聊树链剖分主要处理的问题是什么把,对象一定要是一颗树,并且我们涉及的操作如果包含了对某个节点以及它的全部子节点进行了什么什么操作,如果对着树形结构我们很难处理,但是当我们化树为链的时候就有了很强的数据结构例如线段树、树状数组来帮我们处理区间信息。并且树链剖分很难被卡,常数很优秀,被精心设计的数据还可能卡不掉

这题有个地方调了我比较长的时间,可能这就是对着模板写多了一改改不全的小毛病...就是之前一直写的模板都是遇到叶子节点直接导致只有的左区间,没有右区间,这个数据还是我测单个节点的时候偶然发现的,之前还一直找我线段树的宏是不是写错了,导致线段树出调半天…大家引以为戒把。

#include <bits/stdc++.h>
using namespace std;
#define js ios::sync_with_stdio(false);cin.tie(0); cout.tie(0)
#define all(__vv__) (__vv__).begin(), (__vv__).end()
#define endl "\n"
#define pai pair<int, int>
#define ms(__x__,__val__) memset(__x__, __val__, sizeof(__x__))
#define rep(i, sta, en) for(int i=sta; i<=en; ++i)
#define repp(i, sta, en) for(int i=sta; i>=en; --i)
typedef long long ll; typedef unsigned long long ull; typedef long double ld;
inline ll read() { ll s = 0, w = 1; char ch = getchar(); for (; !isdigit(ch); ch = getchar()) if (ch == '-') w = -1; for (; isdigit(ch); ch = getchar())    s = (s << 1) + (s << 3) + (ch ^ 48); return s * w; }
inline void print(ll x, int op = 10) { if (!x) { putchar('0'); if (op)    putchar(op); return; }    char F[40]; ll tmp = x > 0 ? x : -x;    if (x < 0)putchar('-');    int cnt = 0;    while (tmp > 0) { F[cnt++] = tmp % 10 + '0';        tmp /= 10; }    while (cnt > 0)putchar(F[--cnt]);    if (op)    putchar(op); }
inline ll gcd(ll x, ll y) { return y ? gcd(y, x % y) : x; }
ll qpow(ll a, ll b) { ll ans = 1;    while (b) { if (b & 1)    ans *= a;        b >>= 1;        a *= a; }    return ans; }    ll qpow(ll a, ll b, ll mod) { ll ans = 1; while (b) { if (b & 1)(ans *= a) %= mod; b >>= 1; (a *= a) %= mod; }return ans % mod; }
const int dir[][2] = { {0,1},{1,0},{0,-1},{-1,0},{1,1},{1,-1},{-1,1},{-1,-1} };
const int MOD = 1e9 + 7;
const int INF = 0x3f3f3f3f;

const int N = 1e5 + 7;
int n, m, w[N];
int fa[N], dep[N], sz[N], son[N], top[N], dfn[N], rnk[N], last[N], tot;
vector<int> edge[N];

struct Seg_tree {
#define mid (l + r >> 1)
#define lson rt << 1, l, mid
#define rson rt << 1 | 1, mid + 1, r
#define ls rt << 1
#define rs rt << 1 | 1

    ll sum[N << 2], lazy[N << 2];
    void push_up(int rt) {
        sum[rt] = sum[ls] + sum[rs];
    }
    void push_down(int rt, int l, int r) {
        if (lazy[rt]) {
            sum[ls] += lazy[rt] * (mid - l + 1);
            sum[rs] += lazy[rt] * (r - mid);
            lazy[ls] += lazy[rt];
            lazy[rs] += lazy[rt];
            lazy[rt] = 0;
        }
    }
    void build(int rt, int l, int r) {
        if (l == r) {
            sum[rt] = w[rnk[l]];
            return;
        }
        build(lson);
        build(rson);
        push_up(rt);
    }
    void update(int rt, int l, int r, int L, int R, int v) {
        if (l >= L and r <= R) {
            sum[rt] += 1ll * (r - l + 1) * v;
            lazy[rt] += v;
            return;
        }
        push_down(rt, l, r);
        if (L <= mid)    update(lson, L, R, v);
        if (R > mid)    update(rson, L, R, v);
        push_up(rt);
    }
    ll query_sum(int rt, int l, int r, int L, int R) {
        if (l >= L and r <= R) {
            return sum[rt];
        }
        push_down(rt, l, r);
        ll ans = 0;
        if (L <= mid) ans += query_sum(lson, L, R);
        if (R > mid) ans += query_sum(rson, L, R);
        return ans;
    }
}A;

void dfs1(int u) {
    son[u] = -1;
    sz[u] = 1;
    for (auto& v : edge[u]) {
        if (dep[v])    continue;
        dep[v] = dep[u] + 1;
        fa[v] = u;
        dfs1(v);
        sz[u] += sz[v];
        if (son[u] == -1 or sz[v] > sz[son[u]])
            son[u] = v;
    }
}

void dfs2(int u, int t) {
    top[u] = t;
    dfn[u] = ++tot;
    rnk[tot] = u;
    /*
    if (son[u] == -1)    return;
    dfs2(son[u], t);
    */
    if (son[u] != -1)    dfs2(son[u], t);
    for (auto& v : edge[u])
        if (v != son[u] and v != fa[u])    dfs2(v, v);
    last[u] = tot;
}

ll query_sum(int x, int y) {
    ll res = 0;
    int fx = top[x], fy = top[y];
    while (fx != fy) {
        if (dep[fx] >= dep[fy]) {
            res += A.query_sum(1, 1, n, dfn[fx], dfn[x]);
            x = fa[fx];
        }
        else {
            res += A.query_sum(1, 1, n, dfn[fy], dfn[y]);
            y = fa[fy];
        }
        fx = top[x];
        fy = top[y];
    }
    if (dfn[x] < dfn[y])
        res += A.query_sum(1, 1, n, dfn[x], dfn[y]);
    else
        res += A.query_sum(1, 1, n, dfn[y], dfn[x]);
    return res;
}

void solve() {
    n = read(), m = read();
    rep(i, 1, n)    w[i] = read();
    rep(i, 2, n) {
        int u = read(), v = read();
        edge[u].push_back(v);
        edge[v].push_back(u);
    }
    dep[1] = 1;
    dfs1(1);
    dfs2(1, 1);
    A.build(1, 1, n);
    int op, x, y;
    while (m--) {
        op = read();
        if (op == 1) {
            x = read(), y = read();
            A.update(1, 1, n, dfn[x], dfn[x], y);
        }
        else if (op == 2) {
            x = read(), y = read();
            A.update(1, 1, n, dfn[x], last[x], y);
        }
        else {
            x = read();
            ll ans = query_sum(1, x);
            print(ans);
        }
    }
}

int main() {
    //int T = read();    rep(_, 1, T)
    {
        solve();
    }
    return 0;
}