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"""

Pure Python implementation of a binary search algorithm.

For doctests run following command:

python3 -m doctest -v simple_binary_search.py

For manual testing run:

python3 simple_binary_search.py

"""

from __future__ import annotations

def binary_search(a_list: list[int], item: int) -> bool:

"""

>>> test_list = [0, 1, 2, 8, 13, 17, 19, 32, 42]

>>> binary_search(test_list, 3)

False

>>> binary_search(test_list, 13)

True

>>> binary_search([4, 4, 5, 6, 7], 4)

True

>>> binary_search([4, 4, 5, 6, 7], -10)

False

>>> binary_search([-18, 2], -18)

True

>>> binary_search([5], 5)

True

>>> binary_search(['a', 'c', 'd'], 'c')

True

>>> binary_search(['a', 'c', 'd'], 'f')

False

>>> binary_search([], 1)

False

>>> binary_search([-.1, .1 , .8], .1)

True

>>> binary_search(range(-5000, 5000, 10), 80)

True

>>> binary_search(range(-5000, 5000, 10), 1255)

False

>>> binary_search(range(0, 10000, 5), 2)

False

"""

if len(a_list) == 0:

return False

midpoint = len(a_list) // 2

if a_list[midpoint] == item:

return True

if item < a_list[midpoint]:

return binary_search(a_list[:midpoint], item)

else:

return binary_search(a_list[midpoint + 1 :], item)

if __name__ == "__main__":

user_input = input("Enter numbers separated by comma:\n").strip()

sequence = [int(item.strip()) for item in user_input.split(",")]

target = int(input("Enter the number to be found in the list:\n").strip())

not_str = "" if binary_search(sequence, target) else "not "

print(f"{target} was {not_str}found in {sequence}")

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