[SP10707 COT2] 树上莫队

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#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define per(i,a,b) for(int i=(a);i>=(b);i--)
using namespace std;
const int N=4e5;
struct Q{int l,r,id,add;}q[N];
struct node{int y,n;}e[N<<1];
int lin[N<<1],fa[N][25],deep[N],pos[N],cnt[N],ans[N],v[N],s[N],t[N],a[N],b[N],blo,now=0,tot=0,len=0,l,r,n,tmp,m,x,y;
void read(int x,int y)
{e[++len].y=y,e[len].n=lin[x],lin[x]=len;}
void dfs(int x,int f){
	fa[x][0]=f,s[x]=++tot,pos[tot]=x;
	rep(i,1,20)if((1<<i)<=deep[x])fa[x][i]=fa[fa[x][i-1]][i-1];
	for(int i=lin[x];i;i=e[i].n){
		int y=e[i].y;
		if(y==f)continue;
		deep[y]=deep[x]+1;
		dfs(y,x);
	}t[x]=++tot,pos[tot]=x;
}
int lca(int x,int y){
	if(deep[x]<deep[y])swap(x,y);
	per(i,20,0)if((1<<i)<=deep[x]-deep[y])x=fa[x][i];
	if(x==y)return x;
	per(i,20,0)if(fa[x][i]!=fa[y][i]){
		x=fa[x][i],y=fa[y][i];
	}
	return fa[x][0];
}
bool cmp(Q a,Q b){return (a.l/blo==b.l/blo&&a.r<b.r)||(a.l/blo<b.l/blo);}
void add(int x){int q=a[x];if(cnt[q]==0)++now;++cnt[q];}
void del(int x){int q=a[x];--cnt[q];if(cnt[q]==0)now--;}
void upd(int x){(v[x])? del(x):add(x);v[x]^=1;}
int main()
{
	scanf("%d%d",&n,&m);blo=sqrt(n);
	rep(i,1,n)scanf("%d",&a[i]),b[i]=a[i];
	sort(b+1,b+n+1);
	rep(i,1,n)a[i]=lower_bound(b+1,b+n+1,a[i])-b;
	rep(i,2,n){
		scanf("%d%d",&x,&y);
		read(x,y),read(y,x);
	}
	dfs(1,1);
	rep(i,1,m){
		scanf("%d%d",&x,&y);
		int top=lca(x,y);
		if(s[x]>s[y])swap(x,y);
		if(x==top)q[i].l=s[x],q[i].r=s[y],q[i].id=i;
		else q[i].l=t[x],q[i].r=s[y],q[i].id=i,q[i].add=top;
	}
	sort(q+1,q+m+1,cmp);
	l=1,r=0;
	rep(i,1,m){
		while(l<q[i].l)upd(pos[l++]);
		while(l>q[i].l)upd(pos[--l]);
		while(r>q[i].r)upd(pos[r--]);
		while(r<q[i].r)upd(pos[++r]);
		if(q[i].add)upd(q[i].add);
		ans[q[i].id]=now;
		if(q[i].add)upd(q[i].add);
	}
	rep(i,1,m)printf("%dn",ans[i]);
	return 0;
}