implementing Merge Sort in Swift - Unexpectedly Slow Performance on Large Arrays
I'm relatively new to this, so bear with me... I'm working on a personal project and I'm attempting to implement the Merge Sort algorithm in Swift, but I'm working with performance optimization when sorting large arrays... The implementation seems to work correctly for smaller datasets, but when I test it with arrays larger than 10,000 elements, the execution time increases significantly, making it impractical for real-time applications. Here's the code I've written: ```swift func mergeSort<T: Comparable>(_ array: [T]) -> [T] { guard array.count > 1 else { return array } let middleIndex = array.count / 2 let leftArray = mergeSort(Array(array[0..<middleIndex])) let rightArray = mergeSort(Array(array[middleIndex..<array.count])) return merge(leftArray, rightArray) } func merge<T: Comparable>(_ left: [T], _ right: [T]) -> [T] { var leftIndex = 0 var rightIndex = 0 var sortedArray: [T] = [] while leftIndex < left.count && rightIndex < right.count { if left[leftIndex] < right[rightIndex] { sortedArray.append(left[leftIndex]) leftIndex += 1 } else { sortedArray.append(right[rightIndex]) rightIndex += 1 } } return sortedArray + left[leftIndex...] + right[rightIndex...] } ``` I've already added some basic timing with `Date()` before and after the sort, and on arrays of size 100,000, the sort takes several seconds, which seems excessive. Since I'm using recursion, I worry that it might be due to Swift's stack limitations. I tried adjusting the merge function to avoid creating new arrays for each recursive call but ended up with a memory leak and crashes. I'm not sure if I should be using in-place sorting techniques or if there's something else fundamentally wrong with my approach. Any advice on optimizing this or identifying potential bottlenecks would be greatly appreciated! I'm working on a API that needs to handle this. I'd really appreciate any guidance on this. What's the correct way to implement this? Any examples would be super helpful. I'm on CentOS using the latest version of Swift. Am I missing something obvious?