Given an integer array, nums, sort it in ascending order and return the sorted array.

You must implement the sorting algorithm yourself; do not use any built-in sorting functions. The solution must run in $O(n \log n)$ time and use the minimum possible extra space.

Constraints:

• $1 \leq$ nums.length $\leq 10^3$

• $-10^3 \leq$ nums[i] $\leq 10^3$

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.