From c8f6f79f8038ef090a396725c80fa77d9186fb4b Mon Sep 17 00:00:00 2001
From: Siddharth Warrier <117698635+siddwarr@users.noreply.github.com>
Date: Mon, 9 Oct 2023 01:10:14 +0530
Subject: [PATCH] Power of 4 (#9505)

* added power_of_4

* updated power_of_4

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

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

* updated power_of_4

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

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

* updated power_of_4

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

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

* updated power_of_4

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

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

* updated power_of_4

* added type check

* added tescase

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
---
 bit_manipulation/power_of_4.py | 67 ++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 bit_manipulation/power_of_4.py

diff --git a/bit_manipulation/power_of_4.py b/bit_manipulation/power_of_4.py
new file mode 100644
index 000000000..09e6e2862
--- /dev/null
+++ b/bit_manipulation/power_of_4.py
@@ -0,0 +1,67 @@
+"""
+
+Task:
+Given a positive int number. Return True if this number is power of 4
+or False otherwise.
+
+Implementation notes: Use bit manipulation.
+For example if the number is the power of 2 it's bits representation:
+n     = 0..100..00
+n - 1 = 0..011..11
+
+n & (n - 1) - no intersections = 0
+If the number is a power of 4 then it should be a power of 2
+and the set bit should be at an odd position.
+"""
+
+
+def power_of_4(number: int) -> bool:
+    """
+    Return True if this number is power of 4 or False otherwise.
+
+    >>> power_of_4(0)
+    Traceback (most recent call last):
+        ...
+    ValueError: number must be positive
+    >>> power_of_4(1)
+    True
+    >>> power_of_4(2)
+    False
+    >>> power_of_4(4)
+    True
+    >>> power_of_4(6)
+    False
+    >>> power_of_4(8)
+    False
+    >>> power_of_4(17)
+    False
+    >>> power_of_4(64)
+    True
+    >>> power_of_4(-1)
+    Traceback (most recent call last):
+        ...
+    ValueError: number must be positive
+    >>> power_of_4(1.2)
+    Traceback (most recent call last):
+        ...
+    TypeError: number must be an integer
+
+    """
+    if not isinstance(number, int):
+        raise TypeError("number must be an integer")
+    if number <= 0:
+        raise ValueError("number must be positive")
+    if number & (number - 1) == 0:
+        c = 0
+        while number:
+            c += 1
+            number >>= 1
+        return c % 2 == 1
+    else:
+        return False
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()