Preparando MOJI
There is an array $$$a$$$ consisting of non-negative integers. You can choose an integer $$$x$$$ and denote $$$b_i=a_i \oplus x$$$ for all $$$1 \le i \le n$$$, where $$$\oplus$$$ denotes the bitwise XOR operation. Is it possible to choose such a number $$$x$$$ that the value of the expression $$$b_1 \oplus b_2 \oplus \ldots \oplus b_n$$$ equals $$$0$$$?
It can be shown that if a valid number $$$x$$$ exists, then there also exists $$$x$$$ such that ($$$0 \le x < 2^8$$$).
Each test contains multiple test cases. The first line contains the number of test cases $$$t$$$ ($$$1 \le t \le 1000$$$). The description of the test cases follows.
The first line of the test case contains one integer $$$n$$$ ($$$1 \le n \le 10^3$$$) — the length of the array $$$a$$$.
The second line of the test case contains $$$n$$$ integers — array $$$a$$$ ($$$0 \le a_i < 2^8$$$).
It is guaranteed that the sum of $$$n$$$ over all test cases does not exceed $$$10^3$$$.
For each set test case, print the integer $$$x$$$ ($$$0 \le x < 2^8$$$) if it exists, or $$$-1$$$ otherwise.
531 2 531 2 340 1 2 341 2 2 311
6 0 3 -1 1
In the first test case, after applying the operation with the number $$$6$$$ the array $$$b$$$ becomes $$$[7, 4, 3]$$$, $$$7 \oplus 4 \oplus 3 = 0$$$.
There are other answers in the third test case, such as the number $$$0$$$.
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Provedor Codeforces
Código CF1805A
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Datas 09/05/2023 10:37:45
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