From 4e6c1c049dffdc984232fe1fce1e4791fc527d11 Mon Sep 17 00:00:00 2001
From: Alexander Pantyukhin <apantykhin@gmail.com>
Date: Tue, 1 Nov 2022 21:43:03 +0400
Subject: [PATCH] Is power of two (#7936)

* add is power of two

* fix comment

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Deal with negative numbers

* Spelling: negative

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Christian Clauss <cclauss@me.com>
---
 bit_manipulation/is_power_of_two.py | 57 +++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 bit_manipulation/is_power_of_two.py

diff --git a/bit_manipulation/is_power_of_two.py b/bit_manipulation/is_power_of_two.py
new file mode 100644
index 000000000..023e979fe
--- /dev/null
+++ b/bit_manipulation/is_power_of_two.py
@@ -0,0 +1,57 @@
+"""
+Author  : Alexander Pantyukhin
+Date    : November 1, 2022
+
+Task:
+Given a positive int number. Return True if this number is power of 2
+or False otherwise.
+
+Implementation notes: Use bit manipulation.
+For example if the number is the power of two it's bits representation:
+n     = 0..100..00
+n - 1 = 0..011..11
+
+n & (n - 1) - no intersections = 0
+"""
+
+
+def is_power_of_two(number: int) -> bool:
+    """
+    Return True if this number is power of 2 or False otherwise.
+
+    >>> is_power_of_two(0)
+    True
+    >>> is_power_of_two(1)
+    True
+    >>> is_power_of_two(2)
+    True
+    >>> is_power_of_two(4)
+    True
+    >>> is_power_of_two(6)
+    False
+    >>> is_power_of_two(8)
+    True
+    >>> is_power_of_two(17)
+    False
+    >>> is_power_of_two(-1)
+    Traceback (most recent call last):
+        ...
+    ValueError: number must not be negative
+    >>> is_power_of_two(1.2)
+    Traceback (most recent call last):
+        ...
+    TypeError: unsupported operand type(s) for &: 'float' and 'float'
+
+    # Test all powers of 2 from 0 to 10,000
+    >>> all(is_power_of_two(int(2 ** i)) for i in range(10000))
+    True
+    """
+    if number < 0:
+        raise ValueError("number must not be negative")
+    return number & (number - 1) == 0
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()