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leetcode-problemset/leetcode/problem/chalkboard-xor-game.html

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<p>You are given an array of integers <code>nums</code> represents the numbers written on a chalkboard.</p>
<p>Alice and Bob take turns erasing exactly one number from the chalkboard, with Alice starting first. If erasing a number causes the bitwise XOR of all the elements of the chalkboard to become <code>0</code>, then that player loses. The bitwise XOR of one element is that element itself, and the bitwise XOR of no elements is <code>0</code>.</p>
<p>Also, if any player starts their turn with the bitwise XOR of all the elements of the chalkboard equal to <code>0</code>, then that player wins.</p>
<p>Return <code>true</code> <em>if and only if Alice wins the game, assuming both players play optimally</em>.</p>
<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<pre>
<strong>Input:</strong> nums = [1,1,2]
<strong>Output:</strong> false
<strong>Explanation:</strong>
Alice has two choices: erase 1 or erase 2.
If she erases 1, the nums array becomes [1, 2]. The bitwise XOR of all the elements of the chalkboard is 1 XOR 2 = 3. Now Bob can remove any element he wants, because Alice will be the one to erase the last element and she will lose.
If Alice erases 2 first, now nums become [1, 1]. The bitwise XOR of all the elements of the chalkboard is 1 XOR 1 = 0. Alice will lose.
</pre>
<p><strong class="example">Example 2:</strong></p>
<pre>
<strong>Input:</strong> nums = [0,1]
<strong>Output:</strong> true
</pre>
<p><strong class="example">Example 3:</strong></p>
<pre>
<strong>Input:</strong> nums = [1,2,3]
<strong>Output:</strong> true
</pre>
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>
<ul>
<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
<li><code>0 &lt;= nums[i] &lt; 2<sup>16</sup></code></li>
</ul>