hdu 4358 Boring counting

題意：給出一棵樹，每個點有一個點權，問一x爲根的子樹中有多少種權重恰好出現了k次。

懶了，直接貼題解，況且本來也不是自己寫出來的

#include <cstdio>
#include <cstring>
#include <algorithm>
#include<cmath>
#include<map>
using namespace std;
const int maxn = 100010;
struct node {
	int be, ne;
	void init(int b, int e) {
		be = b;
		ne = e;
	}
} buf[maxn * 2];
struct query {
	int id, from, to;
	bool operator <(const query &oth) const {
		return to < oth.to;
	}
} qq[maxn];
int E[maxn], len;
void add(int a, int b) {
	buf[len].init(b, E[a]);
	E[a] = len++;
	buf[len].init(a, E[b]);
	E[b] = len++;
}
int cnt, id[maxn];
int ss[maxn];
int color[maxn], ans[maxn], cas, n, k, a, b, m;
map<int, int> mp;
int head[maxn], nxt[maxn], last[maxn], num[maxn];
void init(int n) {
	for (int i = 1; i <= n; i++) {
		E[i] = -1;
		qq[i].from = qq[i].to = 0;
		qq[i].id = i;
		ss[i] = num[i] = head[i] = 0;
	}
	mp.clear();
	len = 0;
	cnt = 0;
}
void dfs(int a) {
	qq[a].from = qq[a].to = ++cnt;
	id[cnt] = a;
	for (int i = E[a]; i != -1; i = buf[i].ne) {
		int b = buf[i].be;
		if (qq[b].from)
			continue;
		dfs(b);
		qq[a].to = qq[b].to;
	}
}
int lowbit(int k) {
	return (k & -k);
}
void inc(int i, int k) {
	while (i <= n) {
		ss[i] += k;
		i += lowbit(i);
	}
}
int get(int i) {
	int res = 0;
	while (i > 0) {
		res += ss[i];
		i -= lowbit(i);
	}
	return res;
}
void update(int from, int to, int v) {
	inc(from, v);
	inc(to + 1, -v);
}
int main() {
	scanf("%d", &cas);
	for (int c = 1; c <= cas; c++) {
		printf("Case #%d:\n", c);
		scanf("%d%d", &n, &k);
		init(n);
		for (int i = 1; i <= n; i++) {
			scanf("%d", color + i);
			mp[color[i]] = 0;
		}
		int cnt = 0;
		for (map<int, int>::iterator it = mp.begin(); it != mp.end(); it++)
			(*it).second = ++cnt;
		for (int i = 1; i <= n; i++)
			color[i] = mp[color[i]];
		for (int i = 1; i < n; i++) {
			scanf("%d %d", &a, &b);
			add(a, b);
		}
		dfs(1);
		sort(qq + 1, qq + n + 1);
		int p = 0;
		for (int i = 1; i <= n; i++) {
			while (p < qq[i].to) {
				p++;
				int t = color[id[p]];
				num[t]++;
				nxt[last[t]] = p;
				last[t] = p;
				if (head[t] == 0)
					head[t] = p;
				if (num[t] == k)
					update(1, head[t], 1);
				if (num[t] == k + 1) {
					update(1, head[t], -1);
					update(head[t] + 1, nxt[head[t]], 1);
				}
				if (num[t] > k + 1) {
					update(head[t] + 1, nxt[head[t]], -1);
					head[t] = nxt[head[t]];
					update(head[t] + 1, nxt[head[t]], 1);
				}
			}
			ans[qq[i].id] = get(qq[i].from);
		}
		scanf("%d", &m);
		while (m--) {
			scanf("%d", &a);
			printf("%d\n", ans[a]);
		}
		if (c != cas)
			printf("\n");
	}
	return 0;
}