Merge Sort Explained: How Divide and Conquer Achieves O(n log n) Sorting

Merge Sort is a classic sorting algorithm that improves on slower O(n²) approaches by using a divide-and-conquer strategy to sort n elements in O(n log n) time. The algorithm works by repeatedly splitting an array into halves until each segment contains a single element, which is inherently sorted. These single-element segments are then merged back together in sorted order, with each merge step comparing the front elements of two already-sorted sub-arrays. A Java implementation demonstrates key details such as safe midpoint calculation to avoid integer overflow and a proper base case to terminate recursion. The divide-and-conquer pattern underlying Merge Sort is widely applicable across computer science beyond sorting alone.