题解 | #有效括号序列#

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param s string字符串
     * @return bool布尔型
     */
    public boolean isValid (String s) {
        // write code here

        Map<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))) {
                    // 存放的是他的映射
                    stack.push(map.get(s.charAt(i)));

                    //
                }else if (stack.size() == 0 && map.containsValue(s.charAt(i))) {
                    return false;
                }else if(stack.size() > 0 && stack.peek() == s.charAt(i)){
                    stack.pop();
                }
            }
            if(stack.isEmpty()) {
                return true;
            }else {
                return false;
            }
    }
}