# Algorithm: Heap-Sort
# Time-Complexity: O(nlogn)
def heap_sort(array)
  array_size = array.size
  adjusted_array = [nil] + array
  (array_size / 2).downto(1) do |i|
    adjusted_down(adjusted_array, i, array_size)
  end
  while array_size > 1
    adjusted_array[1], adjusted_array[array_size] = adjusted_array[array_size], adjusted_array[1]  
    array_size -= 1
    adjusted_down(adjusted_array, 1, array_size)
  end
  adjusted_array.drop(1)
end

#Method to adjust heap in downward manner
def adjusted_down(adjusted_array, parent, limit)
  top = adjusted_array[parent]
  while (child = 2 * parent) <= limit
    child += 1  if child < limit and adjusted_array[child] < adjusted_array[child + 1]  
    break  if top >= adjusted_array[child]
    adjusted_array[parent] = adjusted_array[child]
    parent = child
  end
  adjusted_array[parent] = top
end

#Code for testing heapsort
array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15].shuffle
print heap_sort(array)