From 9ceecd50b679fd215c778f64c49baa4f83b8c5fb Mon Sep 17 00:00:00 2001
From: zhenzi <tianzhenzi@inke.cn>
Date: Sat, 15 May 2021 10:51:53 +0800
Subject: [PATCH] =?UTF-8?q?0020=20=E6=9C=89=E6=95=88=E6=8B=AC=E5=8F=B7?=
 =?UTF-8?q?=E5=A2=9E=E5=8A=A0Java=E6=96=B0=E8=A7=A3=E6=B3=95?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 problems/0020.有效的括号.md | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/problems/0020.有效的括号.md b/problems/0020.有效的括号.md
index 77c6e10a..98cc7cd8 100644
--- a/problems/0020.有效的括号.md
+++ b/problems/0020.有效的括号.md
@@ -162,6 +162,33 @@ class Solution {
         return deque.isEmpty();
     }
 }
+// 方法2
+class Solution {
+    public boolean isValid(String s) {
+
+        Stack<Character> stack = new Stack<>();
+        Map<Character, Character> map = new HashMap<Character, Character>() {
+            {
+                put('}', '{');
+                put(']', '[');
+                put(')', '(');
+            }
+        };
+
+        for (Character c : s.toCharArray()) {               // 顺序读取字符
+            if (!stack.isEmpty() && map.containsKey(c)) {   // 是右括号 && 栈不为空
+                if (stack.peek() == map.get(c)) {               // 取其对应的左括号直接和栈顶比
+                    stack.pop();                                // 相同则抵消，出栈
+                } else {        
+                    return false;                               // 不同则直接返回
+                }
+            } else {                                
+                stack.push(c);                              // 左括号，直接入栈
+            }
+        }
+        return stack.isEmpty();                             // 看左右是否抵消完
+    }
+}
 ```
 
 Python：