main.py

import random

def shiftDown(arr, heap_size, idx):
    while idx * 2 + 1 < heap_size:
        child = idx * 2 + 1
        if child + 1 < heap_size and arr[child] < arr[child + 1]:
            child += 1
        if arr[idx] >= arr[child]:
            break
        arr[idx], arr[child] = arr[child], arr[idx];
        idx = child

def heap_sort(arr):
    for i in range(len(arr) // 2 - 1, -1, -1):
        shiftDown(arr, len(arr), i)
    
    for i in range(len(arr) - 1, 0, -1):
        arr[0], arr[i] = arr[i], arr[0]
        shiftDown(arr, i, 0)
        
def main():
    num = 20
    range_left = 0
    range_right = 10000

    arr = [random.randint(range_left, range_right) for _ in range(num)]
    
    print('Original array:')
    print(arr)

    heap_sort(arr)

    print('Sorted array:')
    print(arr)

if __name__ == '__main__':
    main()