Convert binary search to iterative, add helper functions and main with complexity docstring while preserving functionality (#10552)

Co-authored-by: Arie Bregman <[email protected]>

Author: djeada

Diff for: coding/python/binary_search.py

@@ -1,28 +1,42 @@
 #!/usr/bin/env python
 
 import random
-from typing import List
+from typing import List, Optional
 
 
-def binary_search(arr: List[int], lb: int, ub: int, target: int) -> int:
+def binary_search(arr: List[int], lb: int, ub: int, target: int) -> Optional[int]:
     """
     A Binary Search Example which has O(log n) time complexity.
     """
-    if lb <= ub:
-        mid: int = lb + (ub - lb) // 2
+    while lb <= ub:
+        mid = lb + (ub - lb) // 2
         if arr[mid] == target:
             return mid
         elif arr[mid] < target:
-            return binary_search(arr, mid + 1, ub, target)
+            lb = mid + 1
         else:
-            return binary_search(arr, lb, mid - 1, target)
-    else:
-        return 0
+            ub = mid - 1
+    return -1
+
+
+def generate_random_list(size: int = 10, lower: int = 1, upper: int = 50) -> List[int]:
+    return sorted(random.randint(lower, upper) for _ in range(size))
+
+
+def find_target_in_list(target: int, lst: List[int]) -> int:
+    return binary_search(lst, 0, len(lst) - 1, target)
+
+
+def main():
+    """
+    Executes the binary search algorithm with a randomly generated list.
+    Time Complexity: O(log n)
+    """
+    rand_num_li = generate_random_list()
+    target = random.randint(1, 50)
+    index = find_target_in_list(target, rand_num_li)
+    print(f"List: {rand_num_li}\nTarget: {target}\nIndex: {index}")
 
 
 if __name__ == '__main__':
-    rand_num_li: List[int] = sorted([random.randint(1, 50) for _ in range(10)])
-    target: int = random.randint(1, 50)
-    print("List: {}\nTarget: {}\nIndex: {}".format(
-        rand_num_li, target,
-        binary_search(rand_num_li, 0, len(rand_num_li) - 1, target)))
+    main()