Implementing the Merge Sort Algorithm in Java

Merge sort is an efficient sorting algorithm based on the divide-and-conquer paradigm, with three core steps: divide, conquer, and merge. It recursively splits the array into single-element subarrays, sorts these subarrays, and finally merges two ordered subarrays into a fully ordered array. In Java implementation, the `mergeSort` method recursively divides the array into left and right halves, sorts each half, and then calls the `merge` method to combine them. The `merge` method uses three pointers to traverse the left and right subarrays, compares elements, and fills the result array, while directly copying remaining elements. Algorithm complexity: Time complexity is O(n log n) (each merge operation takes O(n) time, with log n recursive levels), space complexity is O(n) (requires extra space for storing merged results), and it is a stable sort (relative order of equal elements is preserved). Merge sort has a clear logic and is suitable for large-scale data sorting. It serves as a classic example of divide-and-conquer algorithms, efficiently sorting by recursively splitting and merging ordered subarrays.