Merge Sort Bug and Fix Implementation

Bug Identification and Resolution

Bug:

The code has a bug where the original array is not being sorted correctly within the merge_sort function. The function is repeatedly breaking down the array into smaller subarrays but is not merging them back properly in a sorted manner.

Fix:

To resolve this bug, a merge function needs to be implemented within the merge_sort function to merge the sorted subarrays back into a single sorted array.

def merge_sort(arr):
    if len(arr) > 1:
        mid = len(arr) // 2
        left_half = arr[:mid]
        right_half = arr[mid:]

        merge_sort(left_half)
        merge_sort(right_half)

        i = j = k = 0
        while i < len(left_half) and j < len(right_half):
            if left_half[i] < right_half[j]:
                arr[k] = left_half[i]
                i += 1
            else:
                arr[k] = right_half[j]
                j += 1
            k += 1

        while i < len(left_half):
            arr[k] = left_half[i]
            i += 1
            k += 1

        while j < len(right_half):
            arr[k] = right_half[j]
            j += 1
            k += 1

    return arr

def merge(left_half, right_half, arr):
    i = j = k = 0
    while i < len(left_half) and j < len(right_half):
        if left_half[i] < right_half[j]:
            arr[k] = left_half[i]
            i += 1
        else:
            arr[k] = right_half[j]
            j += 1
        k += 1

    while i < len(left_half):
        arr[k] = left_half[i]
        i += 1
        k += 1

    while j < len(right_half):
        arr[k] = right_half[j]
        j += 1
        k += 1

arr = [38, 27, 43, 3, 9, 82, 10]
merge_sort(arr)
print(arr)

Suggestions:

• Use a merge function to merge sorted subarrays.
• Ensure that the main array is being sorted properly within the merge_sort function.