simple_binary_search.py

"""
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__ importannotations


defbinary_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
 """
iflen(a_list) ==0:
returnFalse
midpoint=len(a_list) //2
ifa_list[midpoint] ==item:
returnTrue
ifitem<a_list[midpoint]:
returnbinary_search(a_list[:midpoint], item)
else:
returnbinary_search(a_list[midpoint+1 :], item)


if__name__=="__main__":
user_input=input("Enter numbers separated by comma:\n").strip()
sequence= [int(item.strip()) foriteminuser_input.split(",")]
target=int(input("Enter the number to be found in the list:\n").strip())
not_str=""ifbinary_search(sequence, target) else"not "
print(f"{target} was {not_str}found in {sequence}")