Maximum Xor Secondary
题意翻译
题目大意:
给出一个长为n的正整数序列。定义一个序列的所有数异或的结果为其最大值和次大值的异或值。求在此序列的所有子串(即要求连续一段区间)中价值最大是多少。
输入:
第一行一个整数n($1≤n≤10^5$),表示序列长度。
第二行n个由空格隔开的正整数$s_i$(($1≤s_i≤10^9$)),为序列元素。
输出仅一个整数,即最大异或和。
题目描述
Bike loves looking for the second maximum element in the sequence. The second maximum element in the sequence of distinct numbers $ x_{1},x_{2},...,x_{k} $ $ (k>1) $ is such maximum element $ x_{j} $ , that the following inequality holds: ![](https://cdn.luogu.com.cn/upload/vjudge_pic/CF280B/cbffb592db1e3f6cc63c23bba8878833c080a3b3.png).
The lucky number of the sequence of distinct positive integers $ x_{1},x_{2},...,x_{k} $ $ (k>1) $ is the number that is equal to the bitwise excluding OR of the maximum element of the sequence and the second maximum element of the sequence.
You've got a sequence of distinct positive integers $ s_{1},s_{2},...,s_{n} $ $ (n>1) $ . Let's denote sequence $ s_{l},s_{l+1},...,s_{r} $ as $ s[l..r] $ $ (1<=l<r<=n) $ . Your task is to find the maximum number among all lucky numbers of sequences $ s[l..r] $ .
Note that as all numbers in sequence $ s $ are distinct, all the given definitions make sence.
输入输出格式
输入格式
The first line contains integer $ n $ $ (1<n<=10^{5}) $ . The second line contains $ n $ distinct integers $ s_{1},s_{2},...,s_{n} $ $ (1<=s_{i}<=10^{9}) $ .
输出格式
Print a single integer — the maximum lucky number among all lucky numbers of sequences $ s[l..r] $ .
输入输出样例
输入样例 #1
5
5 2 1 4 3
输出样例 #1
7
输入样例 #2
5
9 8 3 5 7
输出样例 #2
15
说明
For the first sample you can choose $ s[4..5]={4,3} $ and its lucky number is $ (4 xor 3)=7 $ . You can also choose $ s[1..2] $ .
For the second sample you must choose $ s[2..5]={8,3,5,7} $ .