Explain the merge sort algorithm.

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Explain the merge sort algorithm.

The merge sort algorithm is a divide-and-conquer sorting algorithm that works by repeatedly dividing the unsorted list into smaller sublists, sorting those sublists, and then merging them back together to obtain a sorted list.

The algorithm follows these steps:

1. Divide: The unsorted list is divided into two equal-sized sublists (or approximately equal-sized sublists) until each sublist contains only one element. This is done recursively until the base case is reached.

2. Conquer: Each sublist is sorted individually using the merge sort algorithm. This is done by recursively applying the divide and conquer steps.

3. Merge: The sorted sublists are then merged back together to obtain a single sorted list. This is done by comparing the elements from the two sublists and selecting the smaller element to be placed in the final sorted list. This process is repeated until all elements from both sublists are merged.

The key operation in the merge step is the merging of two sorted sublists. It involves comparing the elements from the two sublists and placing them in the correct order in the final sorted list. This process continues until all elements from both sublists are merged.

The merge sort algorithm has a time complexity of O(n log n), where n is the number of elements in the list. This makes it an efficient sorting algorithm for large lists. Additionally, merge sort is a stable sorting algorithm, meaning that it preserves the relative order of equal elements.

Overall, the merge sort algorithm is a reliable and efficient sorting algorithm that utilizes the divide-and-conquer approach to sort a list of elements.