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61 lines
1.3 KiB
Python
61 lines
1.3 KiB
Python
"""
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Author : Naman Sharma
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Date : October 2, 2023
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Task:
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To Find the largest power of 2 less than or equal to a given number.
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Implementation notes: Use bit manipulation.
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We start from 1 & left shift the set bit to check if (res<<1)<=number.
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Each left bit shift represents a pow of 2.
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For example:
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number: 15
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res: 1 0b1
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2 0b10
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4 0b100
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8 0b1000
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16 0b10000 (Exit)
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"""
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def largest_pow_of_two_le_num(number: int) -> int:
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"""
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Return the largest power of two less than or equal to a number.
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>>> largest_pow_of_two_le_num(0)
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0
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>>> largest_pow_of_two_le_num(1)
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1
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>>> largest_pow_of_two_le_num(-1)
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0
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>>> largest_pow_of_two_le_num(3)
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2
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>>> largest_pow_of_two_le_num(15)
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8
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>>> largest_pow_of_two_le_num(99)
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64
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>>> largest_pow_of_two_le_num(178)
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128
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>>> largest_pow_of_two_le_num(999999)
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524288
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>>> largest_pow_of_two_le_num(99.9)
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Traceback (most recent call last):
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...
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TypeError: Input value must be a 'int' type
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"""
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if isinstance(number, float):
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raise TypeError("Input value must be a 'int' type")
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if number <= 0:
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return 0
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res = 1
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while (res << 1) <= number:
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res <<= 1
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return res
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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