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