merge_sort - [Python 3.5]

merge_sort.py

class MergeSort:

    def merge_sort(self, array):

        if len(array) <= 1:
            return array

        midpoint = int(len(array) / 2)

        left = []
        right = []

        for i in range(midpoint):
            left.append(array[i])

        for j in range(midpoint, len(array)):
            right.append(array[j])

        left = self.merge_sort(left)
        right = self.merge_sort(right)

        result = MergeSort.merge(left, right)

        return result

    @staticmethod
    def merge(left, right):

        result = []
        left_pointer = right_pointer = result_pointer = 0

        while left_pointer < len(left) or right_pointer < len(right):

            if left_pointer < len(left) and right_pointer < len(right):

                if left[left_pointer] <= right[right_pointer]:
                    result.append(left[left_pointer])
                    result_pointer += 1
                    left_pointer += 1
                else:
                    result.append(right[right_pointer])
                    result_pointer += 1
                    right_pointer += 1

            elif left_pointer < len(left):
                result.append(left[left_pointer])
                result_pointer += 1
                left_pointer += 1

            elif right_pointer < len(right):
                result.append(right[right_pointer])
                result_pointer += 1
                right_pointer += 1

        return result


def main():
    array = [5, 4, 3, 2, 1]
    print(array)

    result = MergeSort().merge_sort(array)
    print(result)

if __name__ == "__main__":
    main()