Fusionner Trier dans la question Python

def mergeSort(A, l, r):
    if l < r:
        mid = (l + r) // 2
        mergeSort(A, l, mid)
        mergeSort(A, mid + 1, r)
        merge(A, l, mid, r)

def merge(arr, l, mid, r):
    arr1 = []
    arr2 = []

    for i in range(mid):
        arr1.append(arr[i])

    for j in range(mid, r):
        arr2.append(arr[j])

    i = 0
    j = 0
    k = 0

    while (i < len(arr1) and j < len(arr2)):
        if arr1[i] < arr2[j]:
            arr[k] = arr1[i]
            i += 1
        else:   
            arr[k] = arr2[j]
            j += 1
        k += 1

    while i < len(arr1):
        arr[k] = arr1[i]
        i += 1
        k += 1

    while j < len(arr2):
        arr[k] = arr2[j]
        j += 1
        k += 1


arr = [2, 9, 7, 6, 1, 8, 4, 3]
mergeSort(arr, 0, 8)

print(arr)
There's a slight mistake somewhere in the code that I'm not able to find
Please try to run this code on your machine with different test cases.
And Let me know what I'm doing wrong here.
I don't know why I'm getting an incorrect answer: [1, 2, 3, 4, 6, 8, 9, 7]