Summary of one question per day: stack and queue (continuously updated)

20. Valid parenthesis disorder map、 Stack 2021/11/21

Given one only includes ‘(’,’)’,’{’,’}’,’[’,’]’ String s , Determines whether the string is valid .
Valid string needs to meet ： Opening parentheses must be closed with closing parentheses of the same type . The left parenthesis must be closed in the correct order .
Example ：
Input ：s = “()[]{}”
Output ：true
Input ：s = “([)]”
Output ：false

Use unordered_map Unordered Association container . Take advantage of the first in and last out nature of the stack , Traversal string , If ([{ Then push it onto the stack , Otherwise )]}, See whether the element at the top of the stack is its corresponding value , If yes, pop up the stack top element , Finally, if the stack is empty after traversal, it is regarded as valid .

class Solution { 
    
public:
    bool isValid