merge_sort_demo

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# Filename: merge_sort_demo.py
# Version: 1.0.0
# Author: Jeoi Reqi

"""
Description:
    This script demonstrates the Merge Sort algorithm by sorting an array of integers.

Requirements:
    - Python 3.x

Functions:
    - merge_sort(arr):
        Perform merge sort on the given list `arr`.

Usage:
    - Run the script to see the Merge Sort algorithm in action.

Example:

                :: MERGE SORTING DEMO ::

        Original array: [12, 11, 13,  5,  6,  7]
        Sorted array:   [ 5,  6,  7, 11, 12, 13]

        Merge Sorting Complete!

            Exiting Program...   GoodBye!

Additional Notes:
    - Merge Sort is an efficient sorting algorithm with a time complexity of O(n log n).
"""

def merge_sort(arr):
    """
    Perform merge sort on the given list `arr` in place.

    Args:
        arr (list): List of integers to be sorted.

    Returns:
        None. The list `arr` is sorted in place.
    """
    if len(arr) > 1:
        mid = len(arr) // 2
        L = arr[:mid]
        R = arr[mid:]

        merge_sort(L)
        merge_sort(R)

        i = j = k = 0
        while i < len(L) and j < len(R):
            if L[i] < R[j]:
                arr[k] = L[i]
                i += 1
            else:
                arr[k] = R[j]
                j += 1
            k += 1

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

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

def main():
    """
    Main function to demonstrate merge sort.

    It initializes an example array, sorts it using merge_sort function,
    and prints the original and sorted arrays.
    """
    print("\n\t\t:: MERGE SORTING DEMO ::\n")

    # Example array to sort
    arr = [12, 11, 13, 5, 6, 7]

    # Print the original array
    original_arr_str = "["
    for index, num in enumerate(arr):
        if index == 0:
            original_arr_str += f"{num:2}"  # Add one space for single-digit numbers
        else:
            original_arr_str += f", {num:2}"  # Add one space for single-digit numbers
    original_arr_str += "]"
    print("Original array:", original_arr_str)

    # Sort the array using merge sort
    merge_sort(arr)

    # Print the sorted array
    sorted_arr_str = "["
    for index, num in enumerate(arr):
        if index == 0:
            sorted_arr_str += f"{num:2}"  # Add one space for single-digit numbers
        else:
            sorted_arr_str += f", {num:2}"  # Add one space for single-digit numbers
    sorted_arr_str += "]"
    print("Sorted array:  ", sorted_arr_str)

    # Print completion message
    print("\nMerge Sorting Complete!\n\n\tExiting Program...   GoodBye!")

if __name__ == "__main__":
    main()