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47bf3f58e0
* fix validation condition and add tests
* updating DIRECTORY.md
Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
52 lines
1.4 KiB
Python
52 lines
1.4 KiB
Python
# Reference: https://www.geeksforgeeks.org/position-of-rightmost-set-bit/
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def get_index_of_rightmost_set_bit(number: int) -> int:
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"""
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Take in a positive integer 'number'.
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Returns the zero-based index of first set bit in that 'number' from right.
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Returns -1, If no set bit found.
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>>> get_index_of_rightmost_set_bit(0)
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-1
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>>> get_index_of_rightmost_set_bit(5)
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0
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>>> get_index_of_rightmost_set_bit(36)
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2
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>>> get_index_of_rightmost_set_bit(8)
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3
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>>> get_index_of_rightmost_set_bit(-18)
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Traceback (most recent call last):
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...
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ValueError: Input must be a non-negative integer
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>>> get_index_of_rightmost_set_bit('test')
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Traceback (most recent call last):
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...
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ValueError: Input must be a non-negative integer
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>>> get_index_of_rightmost_set_bit(1.25)
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Traceback (most recent call last):
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...
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ValueError: Input must be a non-negative integer
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"""
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if not isinstance(number, int) or number < 0:
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raise ValueError("Input must be a non-negative integer")
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intermediate = number & ~(number - 1)
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index = 0
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while intermediate:
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intermediate >>= 1
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index += 1
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return index - 1
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if __name__ == "__main__":
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"""
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Finding the index of rightmost set bit has some very peculiar use-cases,
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especially in finding missing or/and repeating numbers in a list of
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positive integers.
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"""
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import doctest
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doctest.testmod(verbose=True)
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