rt 求查错/wtcl

#include <bits/stdc++.h>
using namespace std;
#define MAXN 100005
#define lc(p) (p << 1)
#define rc(p) ((p << 1) + 1)

int n, Q, rt, mod;
vector<int> v[MAXN];
int fa[MAXN], siz[MAXN], son[MAXN], dep[MAXN];
int id[MAXN], w[MAXN], wt[MAXN], top[MAXN];
int cnt;

inline void add(int x, int y)
{
    v[x].push_back(y);
    v[y].push_back(x);
}

struct SegmentTree {
    int l, r;
    int sum, add;
} tr[MAXN << 2];

void build(int p, int l, int r)
{
    tr[p].l = l, tr[p].r = r;
    if (l == r) {
        tr[p].sum = w[l];
        return;
    }

    int mid = (l + r) >> 1;
    build(lc(p), l, mid);
    build(rc(p), mid + 1, r);
    tr[p].sum = (tr[lc(p)].sum + tr[rc(p)].sum) % mod;
}

void spr(int p)
{
    if (tr[p].add) {
        tr[lc(p)].sum += tr[p].add * (tr[lc(p)].r - tr[lc(p)].l + 1);
        tr[rc(p)].sum += tr[p].add * (tr[rc(p)].r - tr[rc(p)].l + 1);
        tr[lc(p)].add += tr[p].add;
        tr[rc(p)].add += tr[p].add;
        tr[p].add = 0;
    }
}

void update(int p, int l, int r, int d)
{
    if (l <= tr[p].l && r >= tr[p].r) {
        tr[p].sum += d * (tr[p].r - tr[p].l + 1);
        tr[p].add += d;
        return;
    }
    spr(p);
    int mid = (tr[p].l + tr[p].r) >> 1;
    if (l <= mid)
        update(lc(p), l, r, d);
    if (r > mid)
        update(rc(p), l, r, d);
    tr[p].sum = (tr[lc(p)].sum + tr[rc(p)].sum) % mod;
}

int query(int p, int l, int r)
{
    if (l <= tr[p].l && r >= tr[p].r)
        return tr[p].sum;
    spr(p);
    int mid = (tr[p].l + tr[p].r) >> 1;
    int ans = 0;

    if (l <= mid)
        ans += query(lc(p), l, r);
    if (r > mid)
        ans += query(rc(p), l, r);
    return ans;
}

void dfs1(int p, int f, int depth)
{
    dep[p] = depth;
    fa[p] = f;
    siz[p] = 1;
    int maxson = -1;
    for (vector<int>::iterator it = v[p].begin(); it != v[p].end(); ++it) {
        int to = *it;
        if (to == f)
            continue;
        dfs1(to, p, depth + 1);
        siz[p] += siz[to];
        if (siz[to] > maxson) {
            maxson = siz[to];
            son[p] = to;
        }
    }
}

void dfs2(int p, int linktop)
{
    id[p] = ++cnt;
    top[p] = linktop;
    wt[cnt] = w[p];
    if (!son[p])
        return;
    dfs2(son[p], linktop);
    for (vector<int>::iterator it = v[p].begin(); it != v[p].end(); ++it) {
        int to = *it;
        if (to == fa[p] || to == son[p])
            continue;
        dfs2(to, to);
    }
}

int range_query(int x, int y)
{
    int ans = 0;
    while (top[x] != top[y]) {
        if (dep[top[x]] < dep[top[y]])
            swap(x, y);
        ans += query(1, id[top[x]], id[x]);
        ans %= mod;
        x = fa[top[x]];
    }
    if (dep[x] > dep[y])
        swap(x, y);
    ans += query(1, id[x], id[y]);
    return ans % mod;
}

int son_query(int p)
{
    return query(1, id[p], id[p] + siz[p] - 1) % mod;
}

void range_update(int x, int y, int k)
{
    k %= mod;
    while (top[x] != top[y]) {
        if (dep[top[x]] < dep[top[y]])
            swap(x, y);
        update(1, id[top[x]], id[x], k);
        x = fa[top[x]];
    }
    if (dep[x] > dep[y])
        swap(x, y);
    update(1, id[x], id[y], k);
}

void son_update(int x, int k)
{
    k %= mod;
    update(1, id[x], id[x] + siz[x] - 1, k);
}

signed main()
{
    scanf("%d%d%d%d", &n, &Q, &rt, &mod);
    register int i;
    for (i = 1; i <= n; ++i)
        scanf("%d", &w[i]);
    int x, y;
    for (i = 1; i < n; ++i) {
        scanf("%d%d", &x, &y);
        add(x, y);
    }
    dfs1(rt, 0, 1);
    dfs2(rt, rt);
    build(1, 1, n);

    int op, z;
    while (Q--) {
        scanf("%d%d", &op, &x);
        if (op == 1) {
            scanf("%d%d", &y, &z);
            range_update(x, y, z);
        } else if (op == 2) {
            scanf("%d", &y);
            printf("%d\n", range_query(x, y));
        } else if (op == 3) {
            scanf("%d", &z);
            son_update(x, z);
        } else if (op == 4) {
            printf("%d\n", son_query(x));
        }
    }

    return 0;
}