SH-Quizzes/ACMOJ-2002.cpp

#include<cstdio>
#define unlikely(x)     __builtin_expect(!!(x), 0)
struct char_reader
{
        FILE* f; char *buf,*p1,*p2; int size;
        char_reader(FILE* fin,int bufsize=1<<16) { f=fin; size=bufsize; p1=p2=0; buf=new char[size]; }
        ~char_reader() { delete []buf; }
        inline int operator()() { return p1==p2&&(p2=(p1=buf)+fread(buf,1,size,f),p1==p2)?EOF:*p1++; }
};
struct char_writer
{
        FILE* f; char *buf,*p,*end; int size;
        char_writer(FILE* fout,int bufsize=1<<16) { f=fout; size=bufsize; buf=new char[size]; p=buf; end=buf+bufsize; }
        ~char_writer() { fwrite(buf,p-buf,1,f); delete []buf; }
        inline char operator()(char ch)
        {
                if(unlikely(end==p)) { fwrite(buf,end-buf,1,f); p=buf; }
                return *p++=ch;
        }
};
char_reader gch(stdin);
char_writer wch(stdout);
template<typename T> inline int read(T& t)
{
        bool f=false; int ch; while(ch=gch(),!((ch>='0'&&ch<='9')||ch=='-')) { if(ch==EOF) return 0; }
        t=0;
        if(ch=='-') f=true,ch=gch(); t=ch^48; while(ch=gch(),ch>='0'&&ch<='9') t=(t<<3)+(t<<1)+(ch^48);
        if(f) t=-t;
        return 1;
}
inline int read(char &c)
{
        c=0; int ch; while(ch=gch(),(ch==' '||ch=='\n'||ch=='\r'||ch=='\t')) { if(ch==EOF) return 0; } c=ch;
        return 1;
}
inline int read(char *s)
{
        int ch; while(ch=gch(),(ch==' '||ch=='\n'||ch=='\r'||ch=='\t')) { if(ch==EOF) return 0; }
        *s++=ch; while(ch=gch(),!(ch==' '||ch=='\n'||ch=='\r'||ch=='\t')&&ch!=EOF) *s++=ch;
        return 1;
} inline int read(const char *s) { return read((char*)s); }
inline int readline(char *s)
{
        int ch; while(ch=gch(),(ch==' '||ch=='\n'||ch=='\r'||ch=='\t')) { if(ch==EOF) return 0; }
        *s++=ch; while(ch=gch(),!(ch=='\n'||ch=='\r')&&ch!=EOF) *s++=ch;
        return 1;
} inline int readline(const char *s) { return readline((char*)s); }
template<typename T> inline void write(T t)
{
        int stk[20],cnt=0;
        if(t==0) { wch('0'); return; } if(t<0) { wch('-'); t=-t; }
        while(t>0) { stk[cnt++]=t%10; t/=10; } while(cnt) wch(stk[--cnt]+'0');
}
inline void write(char t) { wch(t); }
inline void write(char *s) { while(*s) wch(*s++); } inline void write(const char *s) { write((char*)s); }
#if __cplusplus >= 201103L
template<typename T,typename... Args> inline int read(T& t,Args&... args) { return read(t)+read(args...); }
template<typename T,typename... Args> inline void write(T t,Args... args) { write(t); write(args...); }
#else
template<typename A_t,typename B_t> inline int read(A_t &a,B_t &b) { return read(a)+read(b); }
template<typename A_t,typename B_t,typename C_t> inline int read(A_t &a,B_t &b,C_t &c) { return read(a)+read(b)+read(c); }
template<typename A_t,typename B_t,typename C_t,typename D_t> inline int read(A_t &a,B_t &b,C_t &c,D_t &d) { return read(a)+read(b)+read(c)+read(d); }
template<typename A_t,typename B_t> inline void write(A_t a,B_t b) { write(a); write(b); }
template<typename A_t,typename B_t,typename C_t> inline void write(A_t a,B_t b,C_t c) { write(a); write(b); write(c); }
template<typename A_t,typename B_t,typename C_t,typename D_t> inline void write(A_t a,B_t b,C_t c,D_t d) { write(a); write(b); write(c); write(d); }
#endif
#include<cstdio>
#include<algorithm>
#include<unordered_map>
#include<cassert>
using namespace std;
typedef long long LL;
const int maxn=5e5+10;
struct Edge
{
	int v;
	Edge *nxt;
}mem[maxn*2],*G[maxn],*ecnt=mem;
inline void AddEdge(int u,int v)
{
	ecnt->v=v;
	ecnt->nxt=G[u];
	G[u]=ecnt++;
}
int n,m,c[maxn],res[maxn],sub_tree_size[maxn];
vector<pair<int,int>> query[maxn];
struct Data
{
	vector<int> colors;
	unordered_map<int,int> mp;
	vector<int> times_to_numbers;
};
int dfs1(int u,int fa)
{
	sub_tree_size[u]=1;
	for(Edge *it=G[u];it;it=it->nxt)
		if(it->v!=fa)
			sub_tree_size[u]+=dfs1(it->v,u);
	return sub_tree_size[u];
}
Data* dfs2(int u,int fa)
{
	// fprintf(stderr,"visit %d from %d\n",u,fa);
	Data *this_data=nullptr;
	if(sub_tree_size[u]==1)
	{
		this_data=new Data;
		this_data->colors.push_back(c[u]);
		this_data->mp[c[u]]=1;
		this_data->times_to_numbers.push_back(0);
		this_data->times_to_numbers.push_back(1);
		for(int i=0;i<query[u].size();i++)
		{
			int id=query[u][i].first,k=query[u][i].second;
			if(k==1) res[id]=1;
		}
		return this_data;
	}
	vector<Data*> sub_data;
	int main_son=0;
	assert(sub_tree_size[main_son]==0);
	for(Edge *it=G[u];it;it=it->nxt)
		if(it->v!=fa)
		{
			Data *p=dfs2(it->v,u);
			if(sub_tree_size[it->v]>sub_tree_size[main_son])
			{
				main_son=it->v;
				swap(this_data,p);
			}
			if(p!=nullptr) sub_data.push_back(p);
		}
	for(int i=0;i<sub_data.size();i++)
	{
		Data *p=sub_data[i];
		for(int j=0;j<p->colors.size();j++)
		{
			this_data->colors.push_back(p->colors[j]);
			int tms=++this_data->mp[p->colors[j]];
			if(tms>=this_data->times_to_numbers.size())
			{
				this_data->times_to_numbers.push_back(0);
				// assert(tms==this_data->times_to_numbers.size());
			}
			this_data->times_to_numbers[tms]++;
		}
		delete p;
	}
	this_data->colors.push_back(c[u]);
	int tms=++this_data->mp[c[u]];
	if(tms>=this_data->times_to_numbers.size())
	{
		this_data->times_to_numbers.push_back(0);
		// assert(tms==this_data->times_to_numbers.size());
	}
	this_data->times_to_numbers[tms]++;
	for(int i=0;i<query[u].size();i++)
	{
		int id=query[u][i].first,k=query[u][i].second;
		if(k>=this_data->times_to_numbers.size()) continue;
		res[id]=this_data->times_to_numbers[k];
	}
	return this_data;
}
int main()
{
	#ifdef local
	freopen("pro.in","r",stdin);
	#endif
	read(n,m);
	for(int i=1;i<=n;i++) read(c[i]);
	for(int i=1;i<=n-1;i++)
	{
		int x,y; read(x,y);
		AddEdge(x,y); AddEdge(y,x);
	}
	for(int i=1;i<=m;i++)
	{
		int u,k; read(u,k);
		query[u].push_back(make_pair(i,k));
	}
	dfs1(1,0);
	dfs2(1,0);
	for(int i=1;i<=m;i++) write(res[i],'\n');
	return 0;
}