HDU 5536 Chip Factory

Chip Factory

Time Limit: 18000/9000 MS (Java/Others)    Memory Limit: 262144/262144 K (Java/Others)
Total Submission(s): 4023    Accepted Submission(s): 1782

Problem Description

John is a manager of a CPU chip factory, the factory produces lots of chips everyday. To manage large amounts of products, every processor has a serial number. More specifically, the factory produces n chips today, the i-th chip produced this day has a serial number s_i.

At the end of the day, he packages all the chips produced this day, and send it to wholesalers. More specially, he writes a checksum number on the package, this checksum is defined as below:
\max_{i,j,k} (s_i+s_j) \oplus s_k
which i,j,k are three different integers between 1 and n. And \oplus is symbol of bitwise XOR.

Can you help John calculate the checksum number of today?

 

Input

The first line of input contains an integer T indicating the total number of test cases.

The first line of each test case is an integer n, indicating the number of chips produced today. The next line has n integers s_1, s_2, .., s_n, separated with single space, indicating serial number of each chip.

1 \le T \le 1000
3 \le n \le 1000
0 \le s_i \le 10^9
There are at most 10 testcases with n > 100

 

Output

For each test case, please output an integer indicating the checksum number in a line.

 

Sample Input

231 2 33100 200 300

 

Sample Output

6400

 

Source

2015ACM/ICPC亚洲区长春站-重现赛（感谢东北师大）

 

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hujie

题目大意：给你一堆数字，选出三个数求出上面的公式的最大值

暴力可过，不知道为什么把它放在字典树里面，听说是用01字典树，暂时不会，先码住

暴力：

#include<iostream>using namespace std;const int maxn=1010;int a[maxn];int main(){int test;scanf("%d",&test);while(test--){int n;scanf("%d",&n);for(int i=0;i<n;i++) scanf("%d",&a[i]);int ans=-1;for(int i=0;i<n;i++){for(int j=i+1;j<n;j++){for(int k=j+1;k<n;k++){ans=max(ans,(a[i]+a[j])^a[k]);ans=max(ans,(a[i]+a[k])^a[j]);ans=max(ans,(a[j]+a[k])^a[i]);}}}printf("%d\n",ans);}}