[Hacker Rank] Interview Preparation Kit: Miscellaneous: Flipping bits. New way to solve ✅.

Gonzalo Diaz · Gonzalo Diaz · commit 34c3afa6cc96 · 2025-07-21T15:25:01.000-04:00
diff --git a/docs/hackerrank/interview_preparation_kit/miscellaneous/flipping-bits-alt-solution-notes.md b/docs/hackerrank/interview_preparation_kit/miscellaneous/flipping-bits-alt-solution-notes.md
@@ -0,0 +1,14 @@
+# [Miscellaneous: Flipping bits](https://www.hackerrank.com/challenges/flipping-bits)
+
+- Difficulty:  `#easy`
+- Category: `#ProblemSolvingBasic` `#BitManipulation`
+
+## Using bitwise operations
+
+The bitwise NOT operator (~) flips all bits of the number.
+
+The & 0xFFFFFFFF ensures that we only keep the last 32 bits,
+effectively simulating a 32-bit unsigned integer.
+
+This is a more efficient and concise way to achieve the same result
+as the original code, without needing to convert to binary strings.
diff --git a/src/hackerrank/interview_preparation_kit/miscellaneous/flipping_bits_alt.py b/src/hackerrank/interview_preparation_kit/miscellaneous/flipping_bits_alt.py
@@ -0,0 +1,7 @@
+# pylint: disable=line-too-long
+# @link Problem definition [[docs/hackerrank/interview_preparation_kit/miscellaneous/flipping-bits.md]] # noqa
+# @see Solution Notes: [[docs/hackerrank/interview_preparation_kit/miscellaneous/flipping-bits-alt-solution-notes.md]] # noqa
+# pylint: enable=line-too-long
+
+def flippingBitsAlt(number: int) -> int:
+    return ~number & 0xFFFFFFFF
diff --git a/src/hackerrank/interview_preparation_kit/miscellaneous/flipping_bits_test.py b/src/hackerrank/interview_preparation_kit/miscellaneous/flipping_bits_test.py
@@ -3,6 +3,7 @@
 
 from ....lib.loader import loadTestCases
 from .flipping_bits import flippingBits
+from .flipping_bits_alt import flippingBitsAlt
 
 FILE_PATH = str(Path(__file__).resolve().parent)
 
@@ -22,3 +23,8 @@ def test_flipping_bits(self):
                     flippingBits(_tt['input']), _tt['answer'],
                     f"{_} | flippingBits({_tt['input']}) must be "
                     f"=> {_tt['answer']}")
+
+                self.assertEqual(
+                    flippingBitsAlt(_tt['input']), _tt['answer'],
+                    f"{_} | flippingBitsAlt({_tt['input']}) must be "
+                    f"=> {_tt['answer']}")
