master-algorithms-py/book/ebook_src/builtin_structures/permutations_alphanumeric.py
Mia von Steinkirch 41756cb10c 🏣 Clean up for arxiv
2020-03-04 17:47:53 -08:00

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Python
Executable File

#!/usr/bin/env python
__author__ = "bt3"
''' Write code to generate all possible case permutations of a given
lower-cased string
'''
def alpha_permutation(string):
'''
>>> alpha_permutation('0ab')
['0Ab', '0Ab', '0ab', '0ab', '0Ba', '0Ba', '0ba', '0ba', 'ab0', 'a0b', 'a0b', 'b0a', 'b0a', 'ba0']
>>> alpha_permutation('')
''
'''
if len(string) < 2:
return string
result = []
for i, c in enumerate(string):
rest = string[i+1:] + string[:i]
for cc in alpha_permutation(rest):
if cc.isalpha():
result.append(c.upper() + cc)
result.append(c + cc)
return result
if __name__ == '__main__':
import doctest
doctest.testmod()