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master
bit_manipulation/power_of_4.py
67 строк
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Siddharth Warrier
Power of 4 (#9505)
08 окт 2023, 22:40
Не верифицирован
08 окт 2023, 22:40
c8f6f79
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""" 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()