decode-xored-array

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Algorithms

There is a hidden integer array <code>arr</code> that consists of <code>n</code> non-negative integers.

It was encoded into another integer array <code>encoded</code> of length <code>n - 1</code>, such that <code>encoded[i] = arr[i] XOR arr[i + 1]</code>. For example, if <code>arr = [1,0,2,1]</code>, then <code>encoded = [1,2,3]</code>.

You are given the <code>encoded</code> array. You are also given an integer <code>first</code>, that is the first element of <code>arr</code>, i.e. <code>arr[0]</code>.

Return the original array <code>arr</code>. It can be proved that the answer exists and is unique.

&nbsp;
Example 1:

<pre>
Input: encoded = [1,2,3], first = 1
Output: [1,0,2,1]
Explanation: If arr = [1,0,2,1], then first = 1 and encoded = [1 XOR 0, 0 XOR 2, 2 XOR 1] = [1,2,3]
</pre>

Example 2:

<pre>
Input: encoded = [6,2,7,3], first = 4
Output: [4,2,0,7,4]
</pre>

&nbsp;
Constraints:

<ul>
	<li><code>2 &lt;= n &lt;= 104</code></li>
	<li><code>encoded.length == n - 1</code></li>
	<li><code>0 &lt;= encoded[i] &lt;= 105</code></li>
	<li><code>0 &lt;= first &lt;= 105</code></li>
</ul>