#pra\
gma GCC optimize("O3")
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cstdlib>

#include <cstring>
#include <cmath>
#include <string>
#include <cctype>

#include <algorithm>
#include <queue>
#include <stack>

using namespace std;
int N,Q;
int BB[200010],LL[200010];

struct edge{
int ed,next;
}E[1000100];
int head[200010],Ecnt;
//type
struct mx2{int vv[2];};
struct mx4{int vv[4];}MINUS_INF{-0x3f3f3f3f,-0x3f3f3f3f,-0x3f3f3f3f,-0x3f3f3f3f};
//seg_tree
int fa[200010],size[200010];
int sid[200010],scnt,real[200010];
mx4 T[2000100];
//dp
mx4 f[200010];
// code
inline void addEdge(int st,int ed)
{
E[++Ecnt].ed=ed;
E[Ecnt].next=head[st];
head[st]=Ecnt;
}
inline mx4 merge_mx4(mx4 x,mx4 y)
{
mx4 ret=MINUS_INF;
int pa=0,pr=0;
static int a[8];
memcpy(a,&x,sizeof x),memcpy(a+4,&y,sizeof y);
sort(a,a+8,greater<int>());
//int t=unique(a,a+6)-a-1;
//memcpy(&ret,a,min(sizeof ret,sizeof(int)*(t+1)));
while(pr<4&&pa<8)
{
if(pa==0||a[pa]!=a[pa-1]||(pa==1&&a[pa]==a[pa-1]))
ret.vv[pr++]=a[pa];
pa++;
}

return ret;
}
void dfs(int st)
{
//cout<<"dfs in"<<st<<endl;
size[st]=1;
sid[st]=++scnt;
real[scnt]=st;
f[st].vv[0]=BB[st];
for(int i=head[st];i;i=E[i].next)
{
int ed=E[i].ed;
if(ed!=fa[st])
{
fa[ed]=st;
dfs(ed);
size[st]+=size[ed];
f[st]=merge_mx4(f[st],f[ed]);
}
}
//printf("size %d=%d pair[%d,%d]\n",st,size[st],f[st].vv[0],f[st].vv[1]);
}
//seg_tree
void build_tree(int L,int R,int id)
{
if(L==R)
T[id].vv[0]=LL[real[L]];
else
{
int mid=(L+R)>>1;
build_tree(L,mid,id<<1);
build_tree(mid+1,R,id<<1|1);
T[id]=merge_mx4(T[id<<1|1],T[id<<1]);
//T[id]=merge_mx4(T[id],T[id<<1|1]);
}
}
mx4 query(int B,int E,int L,int R,int id)
{
if(L>E||R<B||E<B)
return MINUS_INF;
if(L>=B&&R<=E)
return T[id];
int mid=(L+R)>>1;
return merge_mx4(query(B,E,L,mid,id<<1) , query(B,E,mid+1,R,id<<1|1));
}
//end of seg_tree
void print_mx4(mx4 t)
{
printf("%d %d %d %d\n",t.vv[0],t.vv[1],t.vv[2],t.vv[3]);
}
void solve(mx4 mb,mx4 ml)
{
int ret=0;
for(int i=1;i<=3;++i)
for(int j=0;j<=3;++j)
{
int tmp=max(mb.vv[i],mb.vv[i]+ml.vv[j]);
if(tmp!=mb.vv[0])
tmp=min(tmp,mb.vv[0]);
else
tmp=0;
ret=max(ret,tmp);
}
printf("%d\n",max(ret,0));
}
int main()
{
//freopen("C:\Users\Administrator\Downloads\1\Input\soldier14.in","r+",stdin);
//freopen("1.txt","w+",stdout);
scanf("%d%d",&N,&Q);
for(int i=2;i<=N;++i)
{
int x;
scanf("%d",&x);
addEdge(i,x);
addEdge(x,i);
}
for(int i=1;i<=N;++i)
scanf("%d%d",BB+i,LL+i);
memset(f,0xc0,sizeof f);
memset(T,0xc0,sizeof T);
dfs(1);
build_tree(1,N,1);
//printf("\t%d %d\n",LL[real[1]],real[1]);
//print_mx4( query(1,1,1,N,1) );
for(int i=1;i<=Q;++i)
{
int r;
scanf("%d",&r);
mx4 t1,t2;
t1=f[r];
t2=merge_mx4( query(sid[1],sid[r]-1,1,N,1) , query(sid[r]+size[r],N,1,N,1) );
//print_mx4(query(sid[1],sid[r]-1,1,N,1)),print_mx4(query(sid[r]+size[r],N,1,N,1));
//print_mx4(t1);
//print_mx4(t2);
solve(t1,t2);
}
return 0;
}

感谢dicboust提供题解。
这个95分，大略就是维护第一大第二大第三大值之类的。因为很容易证明a%b<b所以尽量往上界加。但是注意不要a+c==b这样就前功尽弃啦。反正这个题解应该是写复杂了，主要就是处理这种特殊情况，必须搞个第三大值。最后5分实在是写不出来啦。
#include <bits/stdc++.h>
using namespace std;
inline int read()
{
char ch=getchar();
int x=0;
while(!isdigit(ch))
ch=getchar();
while(isdigit(ch))
{
x=x*10+ch-'0';
ch=getchar();
}
return x;
}

struct edge
{
int to,nex;
}e[200010];
int point[200010],cnt=0;
inline void add(int x,int y)
{
e[++cnt].to=y;
e[cnt].nex=point[x];
point[x]=cnt;
}

struct node
{
int b,li;
}a[200010];
int n,q,s;
int vis[200010];
int dfn[200010],antidfn[200010],id=0,p[200010];
void dfs(int x)
{
dfn[x]=++id,antidfn[id]=x;
for(int i=point[x];i;i=e[i].nex)
if(!dfn[e[i].to])
dfs(e[i].to);
p[x]=id;
}

struct tree
{
int l,r;
int maxb1,maxb2,max_spe,maxb3;
int maxli1,maxli2;
}t[800010];

void update_b(int i)
{
int tmp[8],j=6;
tmp[0]=t[i<<1].maxb1;
tmp[1]=t[i<<1].maxb2;
tmp[2]=t[i<<1].maxb3;
tmp[3]=t[i<<1].max_spe;
tmp[4]=t[i<<1|1].maxb1;
tmp[5]=t[i<<1|1].maxb2;
tmp[6]=t[i<<1|1].maxb3;
tmp[7]=t[i<<1|1].max_spe;
sort(tmp,tmp+8);
t[i].maxb1=tmp[7];
while(tmp[j]==t[i].maxb1)
j--;
t[i].maxb2=tmp[j];
if(j!=6)
t[i].max_spe=tmp[7];
else
t[i].max_spe=0;
while(tmp[j]==t[i].maxb2&&j>0)
j--;
t[i].maxb3=tmp[j];
}
void update_li(int i)
{
int tmp[4];
tmp[0]=t[i<<1].maxli1;
tmp[1]=t[i<<1].maxli2;
tmp[2]=t[i<<1|1].maxli1;
tmp[3]=t[i<<1|1].maxli2;
sort(tmp,tmp+4);
t[i].maxli1=tmp[3];
if(tmp[2]!=tmp[3])
t[i].maxli2=tmp[2];
else
t[i].maxli2=tmp[1];
}

void build(int x,int y,int i)
{
t[i].l=x,t[i].r=y;
if(x==y)
{
t[i].maxb1=a[antidfn[x]].b;
t[i].maxb2=t[i].maxb3=0;
t[i].max_spe=0;
t[i].maxli1=a[antidfn[x]].li;
t[i].maxli2=0;
}
else
{
int mid=(x+y)>>1;
build(x,mid,i<<1);
build(mid+1,y,i<<1|1);
update_b(i);
update_li(i);
}
}

struct query
{
int max1,max2,max3,max_spe;
};
query query_b(int x,int y,int i)
{
query tmp;
if(x<=t[i].l&&t[i].r<=y)
{
tmp.max1=t[i].maxb1;
tmp.max2=t[i].maxb2;
tmp.max3=t[i].maxb3;
tmp.max_spe=t[i].max_spe;
return tmp;
}
int mid=(t[i].l+t[i].r)>>1;
if(y<=mid)
return query_b(x,y,i<<1);
if(x>mid)
return query_b(x,y,i<<1|1);
query tmp1=query_b(x,y,i<<1);
query tmp2=query_b(x,y,i<<1|1);
int tmp_tmp[8],j=6;
tmp_tmp[0]=tmp1.max1;
tmp_tmp[1]=tmp1.max2;
tmp_tmp[2]=tmp1.max3;
tmp_tmp[3]=tmp1.max_spe;
tmp_tmp[4]=tmp2.max1;
tmp_tmp[5]=tmp2.max2;
tmp_tmp[6]=tmp2.max3;
tmp_tmp[7]=tmp2.max_spe;
sort(tmp_tmp,tmp_tmp+8);
tmp.max1=tmp_tmp[7];
while(tmp_tmp[j]==tmp.max1)
j--;
tmp.max2=tmp_tmp[j];
if(j!=6)
tmp.max_spe=tmp_tmp[7];
else
tmp.max_spe=0;
while(tmp_tmp[j]==tmp.max2&&j>0)
j--;
tmp.max3=tmp_tmp[j];
return tmp;
}

query query_li(int x,int y,int i)
{
query tmp;
if(x<=t[i].l&&t[i].r<=y)
{
tmp.max1=t[i].maxli1;
tmp.max2=t[i].maxli2;
return tmp;
}
int mid=(t[i].l+t[i].r)>>1;
if(y<=mid)
return query_li(x,y,i<<1);
if(x>mid)
return query_li(x,y,i<<1|1);
query tmp1=query_li(x,y,i<<1);
query tmp2=query_li(x,y,i<<1|1);
int tmp_tmp[4];
tmp_tmp[0]=tmp1.max1;
tmp_tmp[1]=tmp1.max2;
tmp_tmp[2]=tmp2.max1;
tmp_tmp[3]=tmp2.max2;
sort(tmp_tmp,tmp_tmp+4);
tmp.max1=tmp_tmp[3];
if(tmp_tmp[2]!=tmp_tmp[3])
tmp.max2=tmp_tmp[2];
else
tmp.max2=tmp_tmp[1];
return tmp;
}
int main()
{
//freopen("soldier1.in","r",stdin);
//freopen("soldier.out","w",stdout);
memset(point,0,sizeof(point));
memset(vis,0,sizeof(vis));
int i,x;
n=read(),q=read();
for(i=2;i<=n;i++)
{
x=read();
vis[x]=1;
add(x,i);
}
for(i=1;i<=n;i++)
a[i].b=read(),a[i].li=read();
memset(dfn,0,sizeof(dfn));
dfs(1);
build(1,n,1);
//for(i=1;i<=n*2;i++)
// printf("%d %d %d %d %d\n",t[i].l,t[i].r,t[i].maxb1,t[i].maxb2,t[i].max_spe);
while(q--)
{
s=read();
if(!vis[s])
{
cout<<0<<endl;
continue;
}
query tmp_b=query_b(dfn[s],p[s],1);
query tmp_li1,tmp_li2,tmp_li;
if(dfn[s]!=1)
{
tmp_li1=query_li(1,dfn[s]-1,1);
}
else
tmp_li1.max1=0,tmp_li1.max2=0;
if(p[s]!=n)
{
tmp_li2=query_li(p[s]+1,n,1);
}
else
tmp_li2.max1=0,tmp_li2.max2=0;
int tmp_tmp[4];
tmp_tmp[0]=tmp_li1.max1;
tmp_tmp[1]=tmp_li1.max2;
tmp_tmp[2]=tmp_li2.max1;
tmp_tmp[3]=tmp_li2.max2;
sort(tmp_tmp,tmp_tmp+4);
tmp_li.max1=tmp_tmp[3];
if(tmp_tmp[2]!=tmp_tmp[3])
tmp_li.max2=tmp_tmp[2];
else
tmp_li.max2=tmp_tmp[1];
//printf("%d %d %d %d %d\n",tmp_b.max1,tmp_b.max2,tmp_b.max_spe,tmp_li.max1,tmp_li.max2);
if(tmp_li.max1==0)
{
cout<<tmp_b.max2<<endl;
}
else if(tmp_li.max2==0)
{
if(tmp_b.max1==tmp_b.max_spe)
{
cout<<tmp_b.max1<<endl;
}
else if(tmp_b.max2+tmp_li.max1==tmp_b.max1)
{
cout<<max(tmp_b.max2,tmp_b.max3+tmp_li.max1)<<endl;
}
else
cout<<min(tmp_b.max1,tmp_b.max2+tmp_li.max1)<<endl;
}
else
{
if(tmp_b.max1==tmp_b.max_spe)
{
cout<<tmp_b.max1<<endl;
}
else if(tmp_b.max2+tmp_li.max1==tmp_b.max1)
{
cout<<max(tmp_b.max2+tmp_li.max2,tmp_b.max3+tmp_li.max1)<<endl;
}
else
{
cout<<min(tmp_b.max1,tmp_b.max2+tmp_li.max1)<<endl;
}
}
}
return 0;
}