Merge_Sort_Algorithmn.py

# Merge Sort Algorithmn

# This is a divide and conquer algorithm that divides the input array into two halves, calls itself for the two halves, and then merges the two sorted halves.
def merge_sort(array):
    if len(array) <= 1:
        return
    
    middle_point = len(array) // 2
    left_part = array[:middle_point]
    right_part = array[middle_point:]

    merge_sort(left_part)
    merge_sort(right_part)

    left_array_index = 0
    right_array_index = 0
    sorted_index = 0

    while left_array_index < len(left_part) and right_array_index < len(right_part):
        if left_part[left_array_index] < right_part[right_array_index]:
            array[sorted_index] = left_part[left_array_index]
            left_array_index += 1
        else:
            array[sorted_index] = right_part[right_array_index]
            right_array_index += 1
        sorted_index += 1

    while left_array_index < len(left_part):
        array[sorted_index] = left_part[left_array_index]
        left_array_index += 1
        sorted_index += 1
    
    while right_array_index < len(right_part):
        array[sorted_index] = right_part[right_array_index]
        right_array_index += 1
        sorted_index += 1


# Example usage
if __name__ == '__main__': # This condition ensures that the code inside this block will only be executed if the script is run directly, and not when it is imported as a module in another script.
    numbers = [4, 10, 6, 14, 2, 1, 8, 5]
    print('Unsorted array: ')
    print(numbers)
    merge_sort(numbers)
    print('Sorted array: ')
    print(numbers)
    
## Output:
# Unsorted array:   
# [4, 10, 6, 14, 2, 1, 8, 5]
# Sorted array:
# [1, 2, 4, 5, 6, 8, 10, 14]