"""
A recursive implementation of the insertion sort algorithm
"""
from typing import List
def rec_insertion_sort(collection: List, n: int):
"""
Given a collection of numbers and its length, sorts the collections
in ascending order
:param collection: A mutable collection of comparable elements
:param n: The length of collections
>>> col = [1, 2, 1]
>>> rec_insertion_sort(col, len(col))
>>> print(col)
[1, 1, 2]
>>> col = [2, 1, 0, -1, -2]
>>> rec_insertion_sort(col, len(col))
>>> print(col)
[-2, -1, 0, 1, 2]
>>> col = [1]
>>> rec_insertion_sort(col, len(col))
>>> print(col)
[1]
"""
# Checks if the entire collection has been sorted
if len(collection) <= 1 or n <= 1:
return
insert_next(collection, n - 1)
rec_insertion_sort(collection, n - 1)
def insert_next(collection: List, index: int):
"""
Inserts the '(index-1)th' element into place
>>> col = [3, 2, 4, 2]
>>> insert_next(col, 1)
>>> print(col)
[2, 3, 4, 2]
>>> col = [3, 2, 3]
>>> insert_next(col, 2)
>>> print(col)
[3, 2, 3]
>>> col = []
>>> insert_next(col, 1)
>>> print(col)
[]
"""
# Checks order between adjacent elements
if index >= len(collection) or collection[index - 1] <= collection[index]:
return
# Swaps adjacent elements since they are not in ascending order
collection[index - 1], collection[index] = (
collection[index],
collection[index - 1],
)
insert_next(collection, index + 1)
if __name__ == "__main__":
numbers = input("Enter integers separated by spaces: ")
numbers = [int(num) for num in numbers.split()]
rec_insertion_sort(numbers, len(numbers))
print(numbers)