class Solution: def isValid(self, s: str) -> bool: stack=[] openbracket={ '[':1,'{':2,'(':3, } closebracket={ ']':1,'}':2,')':3, } for i in s: if i not in closebracket: stack.append(i) else: if len(stack)>0: pop_brack=stack.pop() if closebracket[i]==openbracket[pop_brack]: continue else: return False else: return False if len(stack)==0: return True else: return False