20. Valid parentheses (utilizing advanced out of stack)

Leetcode-cn.com/problems/va…

class Solution {
   public static boolean isValid(String s) {
        if (s.length() == 0) {
            return true;
        }
        HashMap<Character, Character> map = new HashMap<>();
        map.put('('.') ');
        map.put('['.'] ');
        map.put('{'.'} '); Stack<Character> Stack = new Stack<>();for (int i = 0; i < s.length(); i++) {
            if (map.containsKey(s.charAt(i))) {
                stack.push(s.charAt(i));
            } else {
                if(stack.isEmpty() || map.get(stack.pop()) ! = s.charAt(i)) {return false; }}}returnstack.isEmpty(); }}Copy the code