bzoj2809: [Apio2012]dispatching 启发式合并splay

/**************************************************************
    Problem: 2809
    User: wangyucheng
    Language: C++
    Result: Accepted
    Time:5432 ms
    Memory:88556 kb
****************************************************************/
 
#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
typedef long long ll;
using namespace std;
#define N 1100000
#define inf 0x6ffffffffffffffLL 
int ch[N][2],siz[N],pre[N];
ll val[N],sum[N];
int rank[N];
int e[N],ne[N*2],v[N*2];
int b[N],nn,n;
ll m;
ll L[N],c[N];
void add(int x,int y){
    ne[++nn]=e[x],e[x]=nn,v[nn]=y;
}
void up(int x){
    siz[x]=siz[ch[x][0]]+siz[ch[x][1]]+1;
    sum[x]=sum[ch[x][0]]+sum[ch[x][1]]+val[x];
}
void rotate(int x){
    int y=pre[x],z=pre[y],k=(ch[y][0]==x);
    pre[ch[y][!k]=ch[x][k]]=y;
    pre[ch[x][k]=y]=x;
    pre[x]=z;
    if(z)ch[z][ch[z][1]==y]=x;  
    up(y);
}
void splay(int x,int fa){
    for(;pre[x]!=fa;){
        int y=pre[x],z=pre[y];
        if(z==fa)rotate(x);
        else if((ch[z][1]==y)==(ch[y][1]==x))rotate(y),rotate(x);
        else rotate(x),rotate(x);
    }
    up(x);
}
int select(int x,int k){
    while(siz[ch[x][0]]+1!=k){
        if(k>siz[ch[x][0]]){
            k-=siz[ch[x][0]]+1;
            x=ch[x][1];
        }else x=ch[x][0];
    }
    splay(x,0);
    return x;
}
int cha(int x,int y){
    int now=x,k;
    while(1){
        k=(val[x]<val[y]);   
        if(!ch[x][k]){
            ch[y][0]=0,ch[y][1]=0;
            sum[y]=val[y];
            siz[y]=1;
            ch[x][k]=y;
           pre[y]=x;  
           splay(y,0); 
           break;   
        }else x=ch[x][k];
    }
    return y;
}
int qu[N],bo,he;
int e1;
void bing(int x,int y){
    splay(x,0),splay(y,0);
    if(siz[x]<siz[y])swap(x,y);
    for(qu[bo=he=1]=y;he>=bo;bo++){
       e1=qu[bo];
       if(ch[e1][0])qu[++he]=ch[e1][0];
       if(ch[e1][1])qu[++he]=ch[e1][1]; 
    }
    for(int i=1;i<=he;i++)x=cha(x,qu[i]);
}
ll ans;
void dfs(int x){
   int p=x;
    for(int i=e[x];i;i=ne[i]){
        dfs(v[i]);
        bing(v[i],x);
    }
    splay(x,0);
    int l=0,r=siz[x]+1,mid;
    while(l+1!=r){
        mid=(l+r)>>1;
        x=select(x,mid);
        if(sum[ch[x][0]]+val[x]>m)r=mid;
        else l=mid;
    }
    ans=max(ans,(ll)l*L[p]);
}
int main(){
     scanf("%d%lld",&n,&m);
   for(int i=1;i<=n;i++){
        scanf("%d%lld%lld",&b[i],&c[i],&L[i]);
        if(b[i])add(b[i],i);
   }
    for(int i=1;i<=n;i++){
        siz[i]=1,sum[i]=val[i]=c[i];
    }
    dfs(1);
    cout<<ans;
}