Corrected filename and include static types

searches/simple_binary_search.py

@@ -0,0 +1,53 @@
+"""
+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 typing import List
+
+
+def binary_search(a_list: List[int], item: int) -> bool:
+    """
+    >>> test_list = [0, 1, 2, 8, 13, 17, 19, 32, 42]
+    >>> print(binary_search(test_list, 3))
+    False
+    >>> print(binary_search(test_list, 13))
+    True
+    >>> print(binary_search([4, 4, 5, 6, 7], 4))
+    True
+    >>> print(binary_search([4, 4, 5, 6, 7], -10))
+    False
+    >>> print(binary_search([-18, 2], -18))
+    True
+    >>> print(binary_search([5], 5))
+    True
+    >>> print(binary_search(['a', 'c', 'd'], 'c'))
+    True
+    >>> print(binary_search(['a', 'c', 'd'], 'f'))
+    False
+    >>> print(binary_search([], 1))
+    False
+    >>> print(binary_search([.1, .4 , -.1], .1))
+    True
+    """
+    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}")