c++ merge sort

Merge sort is a popular sorting algorithm that follows the divide-and-conquer approach. It works by recursively dividing the input array into smaller subarrays until they become trivially sorted, and then merging these subarrays to produce the final sorted array. Here is an explanation of each step in the merge sort algorithm:

1. Divide: The first step is to divide the input array into two equal-sized subarrays. This is done by finding the middle index of the array and splitting it into two halves.

2. Conquer: Next, recursively sort the two subarrays created in the previous step. This is done by applying the merge sort algorithm to each subarray separately.

3. Merge: Once the two subarrays are sorted, merge them back together to create a single sorted array. This involves comparing the elements from the two subarrays and placing them in the correct order in the original array.

4. Repeat: Repeat steps 1-3 for each recursively divided subarray until all subarrays are trivially sorted (i.e., they contain only one element).

By following these steps, merge sort ensures that the final array is sorted in ascending order. It has a time complexity of O(n log n), making it an efficient sorting algorithm for large datasets.