Bzoj 3166 heoi2013 Alo persistent trie tree

Given a non-repeating sequence A, you can select an interval in A to obtain the greatest difference or value between the subintervals in the interval and any other number in the interval.

First, we enumerate the secondary values. For a secondary value, the value range of another number may be (L, R) here, l is the second number on the left, which is greater than it. r is the second number on the right, which is greater than it.

Search for the maximum value in the trie tree in this interval.

How can we find this interval? We maintain a balance tree that adds subscripts to the balance tree from the largest to the smallest. Each subscript that adds a subscript larger than the subscripts is in the balance tree. The result is that R is used twice. l

I am too lazy to write set ......

#include<set>#include<cstdio>#include<cstring>#include<iostream>#include<algorithm>#define M 50500#define ls son[0]#define rs son[1]using namespace std;struct Trie{Trie *son[2];int cnt;}*tree[M],mempool[M*40],*C=mempool;int n,maxnum,ans,a[M],l[M],r[M];pair<int,int>b[M];set<int>s;set<int>::iterator it;inline Trie* New_Node(Trie *_,Trie *__,int ___){C->ls=_;C->rs=__;C->cnt=___;return C++;}Trie* Build_Tree(Trie *p,int x,int pos){if(!pos)return New_Node(0x0,0x0,p->cnt+1);if(~x&pos)return New_Node(Build_Tree(p->ls,x,pos>>1),p->rs,p->cnt+1);elsereturn New_Node(p->ls,Build_Tree(p->rs,x,pos>>1),p->cnt+1);}int Get_Ans(Trie *l,Trie *r,int x,int pos){int num=x&pos?1:0;if(!pos)return 0;if(r->son[!num]->cnt-l->son[!num]->cnt)return pos + Get_Ans(l->son[!num],r->son[!num],x,pos>>1);elsereturn Get_Ans(l->son[num],r->son[num],x,pos>>1);}inline int Get_L(int x){it=s.find(x);if(it--==s.begin()) return 0;if(it--==s.begin()) return 0;return *it;}inline int Get_R(int x){it=s.find(x);if(++it==s.end()) return n+1;if(++it==s.end()) return n+1;return *it;}int main(){int i;cin>>n;for(i=1;i<=n;i++){scanf("%d",&a[i]);b[i].first=a[i];b[i].second=i;maxnum=max(maxnum,a[i]);}sort(b+1,b+n+1);for(i=n;i;i--){s.insert(b[i].second);l[b[i].second]=Get_L(b[i].second);r[b[i].second]=Get_R(b[i].second);}tree[0]=New_Node(C,C,0);for(i=1;i<=n;i++)tree[i]=Build_Tree(tree[i-1],a[i],1<<30);for(i=1;i<=n;i++)if(a[i]!=maxnum)ans=max(Get_Ans(tree[l[i]],tree[r[i]-1],a[i],1<<30),ans);cout<<ans<<endl;}

Bzoj 3166 heoi2013 Alo persistent trie tree