Codeforces 620E - New Year Tree

dfs序 + 状态压缩 + 线段树

#include <bits/stdc++.h>
#define LL long long
using namespace std;
const int N = 4e5 + 10, M = N * 2;
int n, m;
int w[N], h[N], e[M], ne[M], idx;
int id[N], nw[N], sz[N], cnt;
struct Node {
    int l, r;
    LL tag, state;
}tr[N * 4];
void add(int a, int b)
{
    e[idx] = b, ne[idx] = h[a], h[a] = idx ++;
}
void pushup(int u)
{
    tr[u].state = tr[u << 1].state | tr[u << 1 | 1].state;
}
void pushdown(int u)
{
    if (tr[u].tag) {
        tr[u << 1].tag = tr[u].tag;
        tr[u << 1 | 1].tag = tr[u].tag;
        tr[u << 1].state = tr[u].tag;
        tr[u << 1 | 1].state = tr[u].tag;
        tr[u].tag = 0;
    }
}
void build(int u, int l, int r)
{
    if (l == r) {
        LL k = w[nw[l]] - 1;
        k = 1LL << k;
        tr[u] = {l, r, 0, k};
        return;
    }
    tr[u] = {l, r};
    int mid = l + r >> 1;
    build(u << 1, l, mid);
    build(u << 1 | 1, mid + 1, r);
    pushup(u);
}
LL query(int u, int l, int r) 
{
    if (tr[u].l >= l && tr[u].r <= r)   return tr[u].state;
    pushdown(u);
    int mid = tr[u].l + tr[u].r >> 1;
    LL res = 0;
    if (l <= mid)   res = query(u << 1, l, r);
    if (r > mid)    res |= query(u << 1 | 1, l, r);
    return res; 
}
void modify(int u, int l, int r, int x)
{
    if (tr[u].l >= l && tr[u].r <= r)   {
        tr[u].state = 1LL << (x - 1); 
        tr[u].tag = 1LL << (x - 1); 
        return;
    }
    pushdown(u);
    int mid = tr[u].l + tr[u].r >> 1;
    if (l <= mid)   modify(u << 1, l, r, x);
    if (r > mid)    modify(u << 1 | 1, l, r, x);
    pushup(u);
}
int main() {
    memset(h, -1, sizeof h);
    scanf("%d%d", &n, &m);
    for (int i = 1; i <= n; i ++ )  scanf("%d", &w[i]);
    for (int i = 1; i < n; i ++ ) {
        int a, b;
        scanf("%d%d", &a, &b);
        add(a, b), add(b, a);
    }
    function<void(int, int)> dfs = [&](int u, int father) {
        id[u] = ++ cnt, nw[cnt] = u, sz[u] = 1;
        for (int i = h[u]; i != -1; i = ne[i]) {
            int j = e[i];
            if (j == father)  continue;
            dfs(j, u);
            sz[u] += sz[j];
        }
    };
    dfs(1, -1);
    build(1, 1, n);
    while (m -- ) {
        int type, u, c;
        scanf("%d%d", &type, &u);
        if (type == 1) {
            scanf("%d", &c);
            modify(1, id[u], id[u] + sz[u] - 1, c);
        }
        else {
            LL ans = query(1, id[u], id[u] + sz[u] - 1);
            int sum = 0;
            for (int i = 0; i < 60; i ++ )
                sum += (ans >> i & 1);
            printf("%d\n", sum);
        }
    }
    return 0;
}