Skip to main content

Posts

Stack:- 20.Valid Parentheses | 1598. Crawler Log Folder | 232. Implement Queue using Stacks

  Valid Parentheses Given a string  s  containing just the characters  '(' ,  ')' ,  '{' ,  '}' ,  '['  and  ']' , determine if the input string is valid. An input string is valid if: Open brackets must be closed by the same type of brackets. Open brackets must be closed in the correct order. Every close bracket has a corresponding open bracket of the same type. Example 1: Input:   s = "()" Output:   true Example 2: Input:   s = "()[]{}" Output:   true Example 3: Input:   s = "(]" Output:   false Example 4: Input:   s = "([])" Output:   true Example 5: Input:   s = "([)]" Output:   false Constraints: 1 <= s.length <= 10 4 s  consists of parentheses only  '()[]{}' . Solution: class Solution : def isValid ( self , s : str ) -> bool : stack=[] valid={ ")" : "(" , "}" : "{" , "]" : "[" } ...