advanced patterns in Merge Sort Implementation: Recursive Calls Not Merging Correctly in Python 3.10
I'm trying to debug I'm working with unexpected behavior in my implementation of the Merge Sort algorithm in Python 3.10. Specifically, during the merging phase, the sorted output does not seem to reflect the correct order, and at times, duplicates are not handled properly. Here's the code I've written: ```python def merge_sort(arr): if len(arr) > 1: mid = len(arr) // 2 # Find the middle of the array L = arr[:mid] # Left half R = arr[mid:] # Right half merge_sort(L) # Sorting the left half merge_sort(R) # Sorting the right half i = j = k = 0 # Merging the sorted halves while i < len(L) and j < len(R): if L[i] < R[j]: arr[k] = L[i] i += 1 else: arr[k] = R[j] j += 1 k += 1 # Checking for remaining elements while i < len(L): arr[k] = L[i] i += 1 k += 1 while j < len(R): arr[k] = R[j] j += 1 k += 1 return arr # Testing the function arr = [38, 27, 43, 3, 9, 82, 10, 38] print(merge_sort(arr)) # Expected: [3, 9, 10, 27, 38, 38, 43, 82] ``` When I run this code, the output is `None` instead of the expected sorted list. Moreover, if I provide an array with duplicates like `[5, 2, 5, 1, 3]`, it returns `[1, 2, 3, 5, 5]`, which is correct, but the method returns `None`, which makes it confusing since I expected to see the sorted array directly from the print statement. I've checked the merge logic and it seems fine, yet I need to figure out why the return value is `None` and how to make the output clearer. I've also tried adding print statements to debug the recursive calls, but they don't seem to indicate where things might be going wrong. Any insights on how to fix this scenario or improve the implementation would be greatly appreciated!