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regex and while loop solution in Clear category for Brackets by krzysztofrrr
import re
def checkio(expression):
# remove characters other than brackets
all_brackets_chars = re.compile(r'[()\[\]{}]')
only_brackets = ''.join(re.findall(all_brackets_chars,expression))
# remove recursively only closed brackets until no brackets left or we find unclosed ones
while only_brackets:
brackets_before_removal = only_brackets
# remove only closed matching closed brackets
only_brackets = re.sub(r'{}|\[\]|\(\)','',only_brackets)
# after each loop run we should get fewer closed brackets
if only_brackets == brackets_before_removal:
return False
return True
#These "asserts" using only for self-checking and not necessary for auto-testing
if __name__ == '__main__':
assert checkio("((5+3)*2+1)") == True, "Simple"
assert checkio("{[(3+1)+2]+}") == True, "Different types"
assert checkio("(3+{1-1)}") == False, ") is alone inside {}"
assert checkio("[1+1]+(2*2)-{3/3}") == True, "Different operators"
assert checkio("(({[(((1)-2)+3)-3]/3}-3)") == False, "One is redundant"
assert checkio("2+3") == True, "No brackets, no problem"
May 22, 2020
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