LeetCode 日记 20.有效的括号

题目来源：https://leetcode-cn.com/problems/valid-parentheses/

class Solution {
    private static Map<Character,Character> map = new HashMap<Character,Character>();
    public Solution() {
         map.put('#','#');
         map.put('(',')');
         map.put('{','}');
         map.put('[',']');
       } 

    public boolean isValid(String s) {
    
        LinkedList<Character> stack = new LinkedList<Character>();
        stack.push('#');
        for(Character c : s.toCharArray()){
            //左括号入栈
            if(map.containsKey(c)) {
                stack.push(c);
            }
            //栈顶的左括号和当前右括号不匹配
            else if(map.get(stack.pop()) != c){
                return false;
            } 
        }
        return stack.size() == 1;
    }
}