From 766e9729243cd16357555ff4d1e8ece8166337f7 Mon Sep 17 00:00:00 2001
From: bourne-3 <595962708@qq.com>
Date: Sun, 7 Nov 2021 18:59:14 +0800
Subject: [PATCH] =?UTF-8?q?=E6=9C=80=E9=95=BF=E5=9B=9E=E6=96=87=E5=AD=97?=
 =?UTF-8?q?=E4=B8=B2Java=E5=AE=9E=E7=8E=B0?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 problems/0005.最长回文子串.md | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/problems/0005.最长回文子串.md b/problems/0005.最长回文子串.md
index c78b827c..bd572060 100644
--- a/problems/0005.最长回文子串.md
+++ b/problems/0005.最长回文子串.md
@@ -265,6 +265,32 @@ public:
 ## Java
 
 ```java
+// 双指针 中心扩散法
+class Solution {
+    public String longestPalindrome(String s) {
+        String s1 = "";
+        String s2 = "";
+        String res = "";
+        for (int i = 0; i < s.length(); i++) {
+            // 分两种情况：即一个元素作为中心点，两个元素作为中心点
+            s1 = extend(s, i, i);  // 情况1
+            res = s1.length() > res.length() ? s1 : res;
+            s2 = extend(s, i, i + 1);  // 情况2
+            res = s2.length() > res.length() ? s2 : res;
+        }
+        return res;  // 返回最长的
+    }
+    public String extend(String s, int start, int end){
+        String tmp = "";
+        while (start >= 0 && end < s.length() && s.charAt(start) == s.charAt(end)){
+            tmp = s.substring(start, end + 1);  // Java中substring是左闭右开的，所以要+1
+            // 向两边扩散
+            start--;
+            end++;
+        }
+        return tmp;
+    }
+}
 ```
 
 ## Python
@@ -292,11 +318,13 @@ class Solution:
 ## Go
 
 ```go
+
 ```
 
 ## JavaScript
 
 ```js
+
 ```
 
 -----------------------