Method mergeSort

python/0912-sort-an-array.py:23–30

(arr, l, r)

                i += 1

        def mergeSort(arr, l, r):
            if l == r:
                return arr
            m = (l + r) // 2
            mergeSort(arr, l, m)
            mergeSort(arr, m + 1, r)
            merge(arr, l, m, r)
            return arr
        
        return mergeSort(nums, 0, len(nums) - 1)