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Second solution in Clear category for Brackets by colinmcnicholl
def checkio(expression):
"""Input: an expression with different types of brackets as a string.
There are only brackets ("{}" "()" or "[]"), digits
or operators ("+" "-" "*" "/").
Output: A verdict on the correctness of the expression in boolean
(True or False).
"""
brackets = [char for char in expression if char in "{}[]()"]
idx = 0
while len(brackets) > 1:
if brackets[idx] == "{" and brackets[idx + 1] == "}":
del brackets[idx: idx + 2]
idx = 0
elif brackets[idx] == "[" and brackets[idx + 1] == "]":
del brackets[idx: idx + 2]
idx =0
elif brackets[idx] == "(" and brackets[idx + 1] == ")":
del brackets[idx: idx + 2]
idx =0
elif brackets[idx] in ")]}":
break
else:
idx += 1
if len(brackets) == 0:
return True
else:
return False
#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. 5, 2019