Enable Javascript in your browser and then refresh this page, for a much enhanced experience.
Straightforward solution solution in Clear category for Brackets by grutte_pier
brackets = {')' : '(', '}': '{', ']': '['}
def checkio(expression):
""" Keep a stack of opening brackets - when a closing bracket is found,
pop one if they match, otherwise return False.
"""
global brackets
# start with one entry to prevent popping from an empty list
stack = ['']
opening = brackets.values()
closing = brackets.keys()
for c in expression:
if c in opening:
stack.append(c)
elif c in closing:
if brackets[c] != stack.pop():
return False
return len(stack) == 1
#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"
Feb. 14, 2015
