Given an integer array nums, return the largest integer that appears exactly once. If no integer appears only once, return $-1$.

Constraints:

• $1 \leq$ nums.length $\leq 2000$

• $0 \leq$ nums[i] $\leq 1000$

Now, let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

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.