def merge_sort(arr):
    if len(arr) <= 1:
        return arr

    # 分割数组
    mid = len(arr) // 2
    left_half = merge_sort(arr[:mid])
    right_half = merge_sort(arr[mid:])

    # 合并数组
    return merge(left_half, right_half)


def merge(left, right):
    result = []
    i = j = 0

    # 合并两个子数组
    while i < len(left) and j < len(right):
        if left[i] <= right[j]:
            result.append(left[i])
            i += 1
        else:
            result.append(right[j])
            j += 1

    # 加入剩余的元素
    result.extend(left[i:])
    result.extend(right[j:])
    return result