class Solution: def isValid(self , s: str) -> bool: # write code here stack=[] for i in range(0,len(s)): c=s[i] if c=='(' or c=='{' or c=='[': stack.append(c) elif c==')': if stack==[] or stack.pop()!='(': return False elif c=='}': if stack==[] or stack.pop()!='{': return False elif c==']': if stack==[] or stack.pop()!='[': return False if stack!=[]: return False return True