RT，楼主的程序在SPOJ上过了（戳我）但是在洛谷交上去每次都显示CE，求大佬帮忙，谢谢！QWQ

附代码（看不看无所谓，应该没有什么问题）

/* 树上莫队 */

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define rep(i, m, n) for(int i = m; i <= n; i++)
#define per(i, m, n) for(int i = m; i >= n; i--)
#define pb push_back
#define mp make_pair
#define pii pair<int, int> 
#define vi vector<int> 
#define vll vector<ll> 
#define sz(v) (int) v.size()
const int INF = 0x3f3f3f3f;

template<class Ty> 
inline void read(Ty & X) {
    X = 0; Ty flag = 1; char ch = getchar();
    while(ch < '0' || ch > '9') { if (ch == '-') flag = 0; ch = getchar(); }
    while(ch >= '0' && ch <= '9') { X = (X << 1) + (X << 3) + ch - '0'; ch = getchar(); }
    if (!flag) X = ~(X - 1);
}

template<class Ty> 
inline void write(Ty X) {
    if (X < 0) { X = ~(X - 1); putchar('-'); }
    if (X > 9) write(X / 10);
    putchar(X % 10 + '0');
}

const int maxn = 2e5 + 10; 
const int maxt = 20;

struct node {
	int l, r, lca, id;
} T[maxn]; 

int pre[maxn][maxt + 5], depth[maxn], first[maxn], last[maxn], cnt[maxn], ans[maxn], belong[maxn], pos[maxn], a[maxn], vis[maxn], len, now, val[maxn], N, M;

vector<int> G[maxn];

bool cmp(node &a, node &b) {
	return (belong[a.l] ^ belong[b.l]) ? (belong[a.l] < belong[b.l]) : ((belong[a.l] & 1) ? a.r < b.r : a.r > b.r);
}

void dfs(int u, int k) {
	depth[u] = depth[k] + 1, pre[u][0] = k;
	pos[++len] = u; 
	first[u] = len; 
	for (int i = 1; i <= maxt; i++) {
		pre[u][i] = pre[pre[u][i - 1]][i - 1];
	}
	for (int i = 0; i < (int) G[u].size(); i++) {
		int v = G[u][i];
		if (v == k) continue;
		dfs(v, u);
	}
	pos[++len] = u; 
	last[u] = len; 
}

int find(int u, int v) {
	if (depth[u] < depth[v]) swap(u ,v);
	for (int i = maxt; i >= 0; i--) {
		if (depth[pre[u][i]] >= depth[v]) 
			u = pre[u][i];
	}
	if (u == v) return u;
	for (int i = maxt; i >= 0; i--) {
		if (pre[u][i] != pre[v][i]) 
			u = pre[u][i], v = pre[v][i];
	}
	return pre[u][0];
}

void add(int ps) {
	if (vis[ps]) now -= !--cnt[val[ps]];
	else now += !cnt[val[ps]]++;
	vis[ps] ^= 1;
}

int main() {
    read(N), read(M);
    rep(i, 1, N) read(a[i]), val[i] = a[i];
    sort(a + 1, a + N + 1);
    int tot = unique(a + 1, a + N + 1) - (a + 1); 
    rep(i, 1, N) val[i] = lower_bound(a + 1, a + tot + 1, val[i]) - a;
    rep(i, 1, N - 1) {
    	int u, v;
    	read(u), read(v);
    	G[u].pb(v), G[v].pb(u);
    }
    dfs(1, 0); 
    int block = sqrt(2 * N);
    int bnum = ceil((double) 2 * N / block);
    rep(i, 1, bnum) rep(j, (i - 1) * block + 1, i * block) belong[j] = i;
    rep(i, 1, M) {
    	int L, R;
    	read(L), read(R);
    	int lca = find(L, R);
    	if (first[L] > first[R]) swap(L, R);
    	if (L == lca) T[i].l = first[L], T[i].r = first[R];
    	else T[i].l = last[L], T[i].r = first[R], T[i].lca = lca;
    	T[i].id = i;
    }
    sort(T, T + M + 1, cmp);
    int l = 1, r = 0;
    rep(i, 1, M) {
    	int ql = T[i].l, qr = T[i].r, lca = T[i].lca;
    	while (l < ql) add(pos[l++]);
    	while (l > ql) add(pos[--l]);
    	while (r > qr) add(pos[r--]);
    	while (r < qr) add(pos[++r]);
    	if (lca) add(lca);
    	ans[T[i].id] = now;
    	if (lca) add(lca);
    }
    rep(i, 1, M) write(ans[i]), puts(""); 
    return 0; 
}