algorithms-python/algorithms/bit/bit_operation.py at master · ivan1911/algorithms-python · GitHub

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"""

Fundamental bit operation:

get_bit(num, i): get an exact bit at specific index

set_bit(num, i): set a bit at specific index

clear_bit(num, i): clear a bit at specific index

update_bit(num, i, bit): update a bit at specific index

"""

This function shifts 1 over by i bits, creating a value being like 0001000. By

performing an AND with num, we clear all bits other than the bit at bit i.

Finally we compare that to 0

"""

def get_bit(num, i):

return (num & (1 << i)) != 0

"""

This function shifts 1 over by i bits, creating a value being like 0001000. By

performing an OR with num, only value at bit i will change.

"""

def set_bit(num, i):

return num | (1 << i)

"""

This method operates in almost the reverse of set_bit

"""

def clear_bit(num, i):

mask = ~(1 << i)

return num & mask

"""

To set the ith bit to value, we first clear the bit at position i by using a

mask. Then, we shift the intended value. Finally we OR these two numbers

"""

def update_bit(num, i, bit):

mask = ~(1 << i)

return (num & mask) | (bit << i)

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