Given an array of integers, where every element appears twice except for one, find the element that occurs only once.

Note: The solution must have linear runtime and constant space complexity.

Constraints:

• $1 \leq$ nums.length $\leq 10^3$
• $-3 \times 10^3 \leq$ nums[i] $\leq 3 \times 10^3$

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We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Implement your solution in the following coding playground: