Quick Sort 3 Partition

def quick_sort_3partition(sorting: list, left: int, right: int) -> None:
    if right <= left:
        return
    a = i = left
    b = right
    pivot = sorting[left]
    while i <= b:
        if sorting[i] < pivot:
            sorting[a], sorting[i] = sorting[i], sorting[a]
            a += 1
            i += 1
        elif sorting[i] > pivot:
            sorting[b], sorting[i] = sorting[i], sorting[b]
            b -= 1
        else:
            i += 1
    quick_sort_3partition(sorting, left, a - 1)
    quick_sort_3partition(sorting, b + 1, right)


def quick_sort_lomuto_partition(sorting: list, left: int, right: int) -> None:
    """
    A pure Python implementation of quick sort algorithm(in-place)
    with Lomuto partition scheme:
    https://en.wikipedia.org/wiki/Quicksort#Lomuto_partition_scheme

    :param sorting: sort list
    :param left: left endpoint of sorting
    :param right: right endpoint of sorting
    :return: None

    Examples:
    >>> nums1 = [0, 5, 3, 1, 2]
    >>> quick_sort_lomuto_partition(nums1, 0, 4)
    >>> nums1
    [0, 1, 2, 3, 5]
    >>> nums2 = []
    >>> quick_sort_lomuto_partition(nums2, 0, 0)
    >>> nums2
    []
    >>> nums3 = [-2, 5, 0, -4]
    >>> quick_sort_lomuto_partition(nums3, 0, 3)
    >>> nums3
    [-4, -2, 0, 5]
    """
    if left < right:
        pivot_index = lomuto_partition(sorting, left, right)
        quick_sort_lomuto_partition(sorting, left, pivot_index - 1)
        quick_sort_lomuto_partition(sorting, pivot_index + 1, right)


def lomuto_partition(sorting: list, left: int, right: int) -> int:
    """
    Example:
    >>> lomuto_partition([1,5,7,6], 0, 3)
    2
    """
    pivot = sorting[right]
    store_index = left
    for i in range(left, right):
        if sorting[i] < pivot:
            sorting[store_index], sorting[i] = sorting[i], sorting[store_index]
            store_index += 1
    sorting[right], sorting[store_index] = sorting[store_index], sorting[right]
    return store_index


def three_way_radix_quicksort(sorting: list) -> list:
    """
    Three-way radix quicksort:
    https://en.wikipedia.org/wiki/Quicksort#Three-way_radix_quicksort
    First divide the list into three parts.
    Then recursively sort the "less than" and "greater than" partitions.

    >>> three_way_radix_quicksort([])
    []
    >>> three_way_radix_quicksort([1])
    [1]
    >>> three_way_radix_quicksort([-5, -2, 1, -2, 0, 1])
    [-5, -2, -2, 0, 1, 1]
    >>> three_way_radix_quicksort([1, 2, 5, 1, 2, 0, 0, 5, 2, -1])
    [-1, 0, 0, 1, 1, 2, 2, 2, 5, 5]
    """
    if len(sorting) <= 1:
        return sorting
    return (
        three_way_radix_quicksort([i for i in sorting if i < sorting[0]])
        + [i for i in sorting if i == sorting[0]]
        + three_way_radix_quicksort([i for i in sorting if i > sorting[0]])
    )


if __name__ == "__main__":
    import doctest

    doctest.testmod(verbose=True)

    user_input = input("Enter numbers separated by a comma:\n").strip()
    unsorted = [int(item) for item in user_input.split(",")]
    quick_sort_3partition(unsorted, 0, len(unsorted) - 1)
    print(unsorted)
Algerlogo

Β© Alger 2022

About us

We are a group of programmers helping each other build new things, whether it be writing complex encryption programs, or simple ciphers. Our goal is to work together to document and model beautiful, helpful and interesting algorithms using code. We are an open-source community - anyone can contribute. We check each other's work, communicate and collaborate to solve problems. We strive to be welcoming, respectful, yet make sure that our code follows the latest programming guidelines.