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First solution in Clear category for Brackets by welv
def checkio(expression):
last=[]
for x in expression:
if x=="{" or x=="(" or x=="[":
last.append(x)
if x=="}":
if len(last)<=0 or last[-1]!="{":
return False
last.pop()
if x==")":
if len(last)<=0 or last[-1]!="(":
return False
last.pop()
if x=="]":
if len(last)<=0 or last[-1]!="[":
return False
last.pop()
if len(last)>0:
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"
Jan. 20, 2017
