diff --git a/src/__pycache__/string_reversal.cpython-312.pyc b/src/__pycache__/string_reversal.cpython-312.pyc
index 1841456..41b8c3a 100644
Binary files a/src/__pycache__/string_reversal.cpython-312.pyc and b/src/__pycache__/string_reversal.cpython-312.pyc differ
diff --git a/src/string_utils.py b/src/string_utils.py
index 63a44a0..2bd3d9d 100644
--- a/src/string_utils.py
+++ b/src/string_utils.py
@@ -1,4 +1,4 @@
-def reverse_string(input_string):
+def reverse_string(input_string: str) -> str:
     """
     Reverse the given string using a manual character-by-character approach.
 
@@ -11,14 +11,12 @@ def reverse_string(input_string):
     Raises:
         TypeError: If the input is not a string.
     """
-    # Type checking
+    # Type checking with additional type hints
     if not isinstance(input_string, str):
         raise TypeError("Input must be a string")
     
-    # Use list to manually reverse the string
-    reversed_chars = []
-    for i in range(len(input_string) - 1, -1, -1):
-        reversed_chars.append(input_string[i])
+    # Use efficient list comprehension for reversal
+    reversed_chars = [input_string[i] for i in range(len(input_string) - 1, -1, -1)]
     
-    # Convert list back to string
+    # Convert list back to string and return
     return ''.join(reversed_chars)
\ No newline at end of file
diff --git a/tests/__pycache__/test_string_reversal.cpython-312-pytest-8.3.5.pyc b/tests/__pycache__/test_string_reversal.cpython-312-pytest-8.3.5.pyc
index 7d4b01b..bfe2877 100644
Binary files a/tests/__pycache__/test_string_reversal.cpython-312-pytest-8.3.5.pyc and b/tests/__pycache__/test_string_reversal.cpython-312-pytest-8.3.5.pyc differ
diff --git a/tests/test_string_utils.py b/tests/test_string_utils.py
index 0a66c5b..abde176 100644
--- a/tests/test_string_utils.py
+++ b/tests/test_string_utils.py
@@ -10,6 +10,10 @@ def test_reverse_string_empty():
     """Test reversal of an empty string."""
     assert reverse_string("") == ""
 
+def test_reverse_string_single_char():
+    """Test reversal of a single character."""
+    assert reverse_string("a") == "a"
+
 def test_reverse_string_with_spaces():
     """Test reversal of strings with spaces."""
     assert reverse_string("hello world") == "dlrow olleh"
@@ -17,6 +21,7 @@ def test_reverse_string_with_spaces():
 def test_reverse_string_special_chars():
     """Test reversal of strings with special characters."""
     assert reverse_string("a!b@c#") == "#c@b!a"
+    assert reverse_string("a1b2c3!@#") == "#@!3c2b1a"
 
 def test_reverse_string_unicode():
     """Test reversal of unicode strings."""