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| #include<iostream>
#include<cstdio>
#include<vector>
using namespace std;
long long read()
{
long long x=0,f=1; char c=getchar();
while(!isdigit(c)){if(c=='-') f=-1;c=getchar();}
while(isdigit(c)){x=x*10+c-'0';c=getchar();}
return x*f;
}
const long long N=300000+100;
const long long M=N*30;
struct SegmentTree
{
#define mid ((now_l+now_r)>>1)
long long son[M][2],cnt;
long long sum[M];
inline void update(long long now)
{
sum[now]=sum[son[now][0]]+sum[son[now][1]];
}
void Build(long long now,long long now_l,long long now_r)
{
if(now_l==now_r)
return;
Build(son[now][0]=++cnt,now_l,mid);
Build(son[now][1]=++cnt,mid+1,now_r);
}
void Add(long long x,long long num,long long now,long long pre,long long now_l,long long now_r)
{
if(now_l==now_r)
{
sum[now]=sum[pre];
sum[now]+=num;
return ;
}
if(x<=mid) son[now][1]=son[pre][1],Add(x,num,son[now][0]=++cnt,son[pre][0],now_l,mid);
else son[now][0]=son[pre][0],Add(x,num,son[now][1]=++cnt,son[pre][1],mid+1,now_r);
update(now);
}
long long Query(long long L,long long R,long long now,long long pre,long long now_l,long long now_r)
{
if(now_l>=L and now_r<=R)
return sum[now]-sum[pre];
long long ans=0;
if(L<=mid) ans+=Query(L,R,son[now][0],son[pre][0],now_l,mid);
if(R>mid) ans+=Query(L,R,son[now][1],son[pre][1],mid+1,now_r);
return ans;
}
void Print(long long now,long long now_l,long long now_r)
{
cerr<<"no."<<now<<" now_l&r:"<<now_l<<" "<<now_r<<" sonl&r"<<son[now][0]<<" "<<son[now][1]<<" sum:"<<sum[now]<<endl;
if(now_l!=now_r)
{
Print(son[now][0],now_l,mid);
Print(son[now][1],mid+1,now_r);
}
}
#undef mid
}sgt;
vector <long long> e[N];
long long n,m,depth[N],size[N],dfn[N],dfn_to,r[N];
void dfs2(long long now)
{
dfn[now]=++dfn_to;
size[now]=1;
for(long long i=0;i<(long long)(e[now].size());i++)
if(depth[e[now][i]]==0)
{
depth[e[now][i]]=depth[now]+1;
dfs2(e[now][i]);
size[now]+=size[e[now][i]];
}
}
void dfs(long long now)
{
r[dfn[now]]=++sgt.cnt;
sgt.Add(depth[now],size[now]-1,r[dfn[now]],r[dfn[now]-1],1,n);
for(long long i=0;i<(long long)(e[now].size());i++)
if(depth[e[now][i]]>depth[now])
dfs(e[now][i]);
}
int main()
{
n=read(),m=read();
for(long long i=1;i<=n;i++)
e[i].reserve(4);
for(long long i=1;i<n;i++)
{
long long s=read(),t=read();
e[s].push_back(t);
e[t].push_back(s);
}
sgt.Build(0,1,n);
depth[1]=1;
dfs2(1);
dfs(1);
for(long long i=1;i<=m;i++)
{
long long p=read(),K=read();
long long ans=sgt.Query(depth[p]+1,depth[p]+K,r[dfn[p]+size[p]-1],r[dfn[p]-1],1,n);
ans+=min(K,depth[p]-1)*(size[p]-1);
printf("%lld\n",ans);
}
return 0;
}
|
