bzoj3166 ALO 可持久化01Trie

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 const int maxn=50005,inf=(int)2e9;
 4 set<int>S;
 5 int ans,bin[35],n;
 6 struct ques
 7 {
 8     int val,pos;
 9     inline bool operator <(const ques &b)const
10     {
11         return val>b.val;
12     }
13 }Q[maxn];
14 struct node
15 {
16     node *ch[2];int sum;
17     node(){}
18     node(int x){sum=x;ch[0]=ch[1]=0x0;}
19 }mempool[maxn*50];int num;
20 node* root[maxn];
21 node* Newnode(int val)
22 {
23     mempool[++num]=node(val);return mempool+num;
24 }
25 void Insert(node* &now,node *las,int val,int deep)
26 {
27     now=Newnode(las->sum+1);
28     if(!(~deep))return;
29     int t=(val>>deep)&1;Insert(now->ch[t],las->ch[t],val,deep-1);now->ch[t^1]=las->ch[t^1];
30 }
31 int Query(node* L,node* R,int val,int deep)
32 {
33     if(!(~deep))return 0;
34     int t=(val>>deep)&1;
35     if(R->ch[t^1]->sum!=L->ch[t^1]->sum)
36         return bin[deep]|Query(L->ch[t^1],R->ch[t^1],val,deep-1);
37     else return Query(L->ch[t],R->ch[t],val,deep-1);
38 }
39 int haha()
40 {
41     bin[0]=1;
42     for(int i=1;i<=30;i++)bin[i]=bin[i-1]<<1;
43     scanf("%d",&n);
44     for(int i=1;i<=n;i++)scanf("%d",&Q[i].val),Q[i].pos=i;
45     root[0]=mempool;root[0]->ch[0]=root[0]->ch[1]=mempool;root[0]->sum=0;
46     for(int i=1;i<=n;i++)Insert(root[i],root[i-1],Q[i].val,31);
47     sort(Q+1,Q+n+1);
48     S.insert(-1),S.insert(inf),S.insert(-2),S.insert(inf+1),S.insert(Q[1].pos);
49     for(int i=2;i<=n;i++)
50     {
51         int l=Q[i].pos,r=Q[i].pos,x=Q[i].pos;
52         set<int>::iterator it=S.lower_bound(x),it2=it;
53         it++;r=(*it)-1;it2--;it2--;l=(*it2)+1;
54         l=max(1,l);r=min(n,r);
55         // cout<<l-1<<" "<<r<<" "<<x<<endl;
56         if(l!=r)ans=max(ans,Query(root[l-1],root[r],Q[i].val,31));
57         S.insert(Q[i].pos);
58     }
59     printf("%d\n",ans);
60 }
61 int sb=haha();
62 int main(){;}