题目传送门：https://codeforces.com/problemset/problem/375/D
题目大意：
给定一个(n)个节点的树，每个节点有颜色(C_x)，给定(m)组询问，每次询问(v_i)及其子树内，出现次数(geqslant k_i)的颜色种数
首先给树上节点打上Dfs序，这样树上询问便可以转化为区间询问
由于没有牵涉到修改，因此我们考虑莫队
每次需要统计次数(geqslant k_i)的颜色种数，故我们用树状数组维护
理论时间复杂度(O(nsqrt n log_2n))，但常数很小，因为莫队跑不满
/*program from Wolfycz*/
#include<map>
#include<cmath>
#include<cstdio>
#include<vector>
#include<cstring>
#include<iostream>
#include<algorithm>
#define Fi first
#define Se second
#define ll_inf 1e18
#define MK make_pair
#define sqr(x) ((x)*(x))
#define pii pair<int,int>
#define int_inf 0x7f7f7f7f
using namespace std;
typedef long long ll;
typedef unsigned int ui;
typedef unsigned long long ull;
inline char gc(){
static char buf[1000000],*p1=buf,*p2=buf;
return p1==p2&&(p2=(p1=buf)+fread(buf,1,1000000,stdin),p1==p2)?EOF:*p1++;
}
template<typename T>inline T frd(T x){
int f=1; char ch=gc();
for (;ch<'0'||ch>'9';ch=gc()) if (ch=='-') f=-1;
for (;ch>='0'&&ch<='9';ch=gc()) x=(x<<1)+(x<<3)+ch-'0';
return x*f;
}
template<typename T>inline T read(T x){
int f=1; char ch=getchar();
for (;ch<'0'||ch>'9';ch=getchar()) if (ch=='-') f=-1;
for (;ch>='0'&&ch<='9';ch=getchar()) x=(x<<1)+(x<<3)+ch-'0';
return x*f;
}
inline void print(int x){
if (x<0) putchar('-'),x=-x;
if (x>9) print(x/10);
putchar(x%10+'0');
}
const int N=1e5;
int pre[(N<<1)+10],now[N+10],child[(N<<1)+10],DFN[N+10],FND[N+10],Sz[N+10];
int Time,tot;
void join(int x,int y){pre[++tot]=now[x],now[x]=tot,child[tot]=y;}
void insert(int x,int y){join(x,y),join(y,x);}
void Dfs(int x,int fa){
FND[DFN[x]=++Time]=x,Sz[x]++;
for (int p=now[x];p;p=pre[p]){
int son=child[p];
if (son==fa) continue;
Dfs(son,x),Sz[x]+=Sz[son];
}
}
int pos[N+10],C[N+10],Cnt[N+10],Ans[N+10];
struct node{
int l,r,K,ID;
node(int _l=0,int _r=0,int _K=0,int _ID=0){l=_l,r=_r,K=_K,ID=_ID;}
bool operator <(const node &tis)const{return pos[l]!=pos[tis.l]?l<tis.l:r<tis.r;}
}Ask[N+10];
struct S1{
#define lowbit(x) ((x)&(-x))
int V[N+10],n;
void Add(int x,int v){for (;x<=n;x+=lowbit(x)) V[x]+=v;}
int Query(int x){
int res=0;
for (;x;x-=lowbit(x)) res+=V[x];
return res;
}
#undef lowbit
}TA;//Tree like Array
int n,m,len;
#define T(x) (n-(x)+1)
void Add(int x,int v){
TA.Add(T(Cnt[C[FND[x]]]),-1);
Cnt[C[FND[x]]]+=v;
TA.Add(T(Cnt[C[FND[x]]]), 1);
}
int Query(int K){return K>n?0:TA.Query(T(K));}
#undef T
int main(){
// freopen(".in","r",stdin);
// freopen(".out","w",stdout);
n=read(0),m=read(0),len=sqrt(n);
for (int i=1;i<=n;i++) C[i]=read(0),pos[i]=(i-1)/len+1;
for (int i=1;i<n;i++){
int x=read(0),y=read(0);
insert(x,y);
}
Dfs(1,0);
for (int i=1;i<=m;i++){
int x=read(0),k=read(0);
Ask[i]=node(DFN[x],DFN[x]+Sz[x]-1,k,i);
}
sort(Ask+1,Ask+1+m); TA.n=n;
for (int i=1,l=1,r=0;i<=m;i++){
while (r<Ask[i].r) Add(++r, 1);
while (r>Ask[i].r) Add(r--,-1);
while (l<Ask[i].l) Add(l++,-1);
while (l>Ask[i].l) Add(--l, 1);
Ans[Ask[i].ID]=Query(Ask[i].K);
}
for (int i=1;i<=m;i++) printf("%d
",Ans[i]);
return 0;
}