bzoj4260 Codechef REBXOR

 1 //It is made by wfj_2048~
 2 #include <algorithm>
 3 #include <iostream>
 4 #include <complex>
 5 #include <cstring>
 6 #include <cstdlib>
 7 #include <cstdio>
 8 #include <vector>
 9 #include <queue>
10 #include <stack>
11 #include <map>
12 #include <set>
13 #define M (15000010)
14 #define N (500010)
15 #define il inline
16 #define RG register
17 #define File(s) freopen(s".in","r",stdin),freopen(s".out","w",stdout)
18 
19 using namespace std;
20 
21 int ch[M][2],sum[M],rt[N],a[N],b[N],n,sz,res,ans;
22 
23 const int STRSIZE=int(4e7);
24 char in1[STRSIZE], *in=in1, *tempend;
25 
26 il int gi(){
27     char c=*(in++); while(c<‘0‘ || c>‘9‘) c=*(in++); RG int x=c-‘0‘;
28     c=*(in++); while (c>=‘0‘ && c<=‘9‘) x=x*10+c-‘0‘,c=*(in++); return x;
29 }
30 
31 il int max(RG int &a,RG int &b){ return a>b ? a : b; }
32 
33 il void insert(RG int x,RG int &now,RG int &v){
34     now=++sz; RG int y=now;
35     for (RG int i=29,tmp;i>=0;--i){
36     tmp=v>>i&1,ch[y][0]=ch[x][0],ch[y][1]=ch[x][1];
37     ch[y][tmp]=++sz,x=ch[x][tmp],y=ch[y][tmp],sum[y]=sum[x]+1;
38     }
39     ch[y][0]=ch[x][0],ch[y][1]=ch[x][1]; return;
40 }
41 
42 il int query(RG int x,RG int y,RG int &v){
43     RG int ans=0;
44     for (RG int i=29,tmp;i>=0;--i){
45     tmp=(v>>i&1)^1;
46     if (sum[ch[y][tmp]]-sum[ch[x][tmp]]) ans|=1<<i,x=ch[x][tmp],y=ch[y][tmp];
47     else x=ch[x][tmp^1],y=ch[y][tmp^1];
48     }
49     return ans;
50 }
51 
52 il void work(){
53     n=gi(); for (RG int i=1;i<=n;++i) a[i]=gi(),b[i]=b[i-1]^a[i],insert(rt[i-1],rt[i],b[i]);
54     for (RG int i=n-1;i;--i){
55     res=max(res,query(rt[i],rt[n],b[i]));
56     ans=max(ans,res+max(b[i],query(rt[0],rt[i],b[i])));
57     }
58     printf("%d\n",ans); return;
59 }
60 
61 int main(){
62     File("xor");
63     tempend=in+STRSIZE;
64     fread(in,1,STRSIZE,stdin);
65     work();
66     return 0;
67 }