BestCoder Round #77 (div.2) 1001 so easy

so easy

 

 Accepts: 518

 

 Submissions: 1601

 Time Limit: 2000/1000 MS (Java/Others)

 

 Memory Limit: 65536/65536 K (Java/Others)

Problem Description

Given an array with n integers, assume $f(S)$ as the result of executing xor operation among all the elements of set $S$. e.g. if $S=\{1,2,3\}$ then $f(S)=0$.

your task is: calculate xor of all $f(s)$, here $s\subseteq S$.

Input

This problem has multi test cases. First line contains a single integer $T(T\le 20)$ which represents the number of test cases. For each test case, the first line contains a single integer number $n(1\le n\le 1,000)$ that represents the size of the given set. then the following line consists of $n$ different integer numbers indicate elements(\leq 10^9≤10​9​​) of the given set.

Output

For each test case, print a single integer as the answer.

Sample Input

1
3
1  2  3

Sample Output

0

In the sample，$S=\{1,2,3\}$, subsets of $S$ are: $\varnothing$, {1}, {2}, {3}, {1, 2}, {1, 3}, {2, 3}, {1, 2, 3}

根据集合子集的规律：所有子集中每个元素出现的总次数为2^(n-1),即此题中当元素个数大于1时相当于每个元素与自身异或2^（n-1）次，结果为0；当元素个数为1 时结果为这个元素本身；

例如：{1,2,3}的结果 =  1^2^3^1^2^1^3^2^3^1^2^3 = 0;一共有四个1，四个2，四个3；