BZOJ3631(树链剖分)

差不多可以说是树链剖分的模板题了，直接维护即可。

#include <bits/stdc++.h>

using namespace std;

#define REP(i,n)                for(int i(0); i <  (n); ++i)

#define rep(i,a,b)              for(int i(a); i <= (b); ++i)

#define dec(i,a,b)              for(int i(a); i >= (b); --i)

#define for_edge(i,x)           for(int i = H[x]; i; i = X[i])

#define LL      long long

#define ULL     unsigned long long

#define MP      make_pair

#define PB      push_back

#define FI      first

#define SE      second

#define INF     1 << 30

const int N     =    300000      +       10;

const int M     =    10000       +       10;

const int Q     =    1000        +       10;

const int A     =    30          +       1;

int E[N << 1], H[N << 1], X[N << 1];

int c[N];

int top[N];

int fa[N];

int deep[N];

int num[N];

int son[N];

int fp[N];

int p[N];

int et, pos;

int a[N];

int n, x, y;

inline int lowbit(int x){ return (x) & (-x);}

inline int query(int x){int ret = 0; for (; x; x -= lowbit(x)) ret += c[x]; return ret;}

inline void add(int x, int val){ for (; x <= n; x += lowbit(x)) c[x] += val;}

inline void addedge(int a, int b){

	E[++et] = b, X[et] = H[a], H[a] = et;

	E[++et] = a, X[et] = H[b], H[b] = et;

}

void dfs(int x, int pre){

	deep[x] = deep[pre] + 1;

	fa[x] = pre;

	num[x] = 1;

	for_edge(i, x){

		int v = E[i];

		if (v != pre){

			dfs(v, x);

			num[x] += num[v];

			if (son[x] != -1 || num[v] > num[son[x]])

				son[x] = v;

		}

	}

}

void getpos(int x, int sp){

	top[x] = sp;

	p[x] = ++pos;

	fp[p[x]] = x;

	if (son[x] == -1) return;

	getpos(son[x], sp);

	for_edge(i, x){

		int v = E[i];

		if (v != son[x] && v != fa[x])

			getpos(v, v);

	}

}

void cover(int u, int v, int val){

	int f1 = top[u], f2 = top[v];

	int tmp = 0;

	while (f1 != f2){

		if (deep[f1] < deep[f2]){

			swap(f1, f2);

			swap(u, v);

		}

		add(p[f1], val);

		add(p[u] + 1, -val);

		u = fa[f1];

		f1 = top[u];

	}

	if (deep[u] > deep[v]) swap(u, v);

	add(p[u], val);

	add(p[v] + 1, -val);

}

int main(){

#ifndef ONLINE_JUDGE

	freopen("test.txt", "r", stdin);

	freopen("test.out", "w", stdout);

#endif

	scanf("%d", &n);

	rep(i, 1, n) scanf("%d", a + i);

	rep(i, 1, n - 1){

		scanf("%d%d", &x, &y);

		addedge(x, y);

	}

	memset(son, -1, sizeof son);

	dfs(1, 0);

	getpos(1, 1);

	rep(i, 1, n - 1){

		x = a[i], y = a[i + 1];

		cover(x, y, 1);

	}

	rep(i, 1, n) if (i == a[1]) printf("%d\n", query(p[i]));

	else printf("%d\n", query(p[i]) - 1);

	return 0;

}