leetcode20.有效的括号

https://leetcode-cn.com/problems/valid-parentheses/

class Solution {
    public boolean isValid(String s) {
        Deque<Character> l = new LinkedList<>();
        char[] arr = s.toCharArray();
        Set<Character> left = new HashSet<>();
        Set<Character> right = new HashSet<>();
        left.add('(');
        left.add('[');
        left.add('{');
        right.add(']');
        right.add(')');
        right.add('}');
        for(int i = 0;i < s.length();i++) {
            if(right.contains(arr[i])) {
                //考虑左括号为空，出现了右括号，则直接返回false
                if(l.size() == 0) return false;
                if(arr[i] == ')' && l.pollLast() == '(') continue;
                if(arr[i] == ']' && l.pollLast() == '[') continue;
                if(arr[i] == '}' && l.pollLast() == '{') continue;
                //如果左右括号不符合，也返回false
                return false;
            } else l.addLast(arr[i]);
        }
        //这里有左右括号都消除了，但是左括号有多余的
        return l.size() == 0 ? true : false;
    }
}

标签：arr,right,false,有效,括号,add,leetcode20,left
来源： https://blog.csdn.net/qq_37931960/article/details/119083531