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iterating_through_submasks is added with doctests

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faizan2700 2019-12-18 10:27:19 +05:30
parent 6e484d8e7c
commit 00351ca899
1 changed files with 22 additions and 9 deletions
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31
dynamic_programming/iterating_through_submasks.py
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@ -1,10 +1,13 @@
'''
"""
Author : Syed Faizan (3rd Year Student IIIT Pune)
github : faizan2700
You are given a bitmask m and you want to efficiently iterate through all of
its submasks. The mask s is submask of m if only bits that were included in
bitmask are set
'''
"""
def list_of_submasks(mask)->list:
def list_of_submasks(mask) -> list:
"""
Args:
@ -21,26 +24,36 @@ def list_of_submasks(mask)->list:
[15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1]
>>> list_of_submasks(13)
[13, 12, 9, 8, 5, 4, 1]
>>> list_of_submasks(-7) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
AssertionError: mask needs to be positive integer, your input -7
>>> list_of_submasks(0) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
AssertionError: mask needs to be positive integer, your input 0
"""
fmt = "n needs to be positive integer, your input {}"
assert isinstance(mask, int) and mask > 0, fmt.format(mask)
'''
"""
first submask iterated will be mask itself then operation will be performed
to get other submasks till we reach empty submask that is zero ( zero is not
included in final submasks list )
'''
"""
all_submasks = []
submask = mask
while submask:
all_submasks.append(submask)
submask = (submask-1) & mask
submask = (submask - 1) & mask
return all_submasks
if __name__ == '__main__':
if __name__ == "__main__":
import doctest
doctest.testmod()