From 3be442c833eb21e1d7084cc44a898bf4ef951627 Mon Sep 17 00:00:00 2001
From: posper <xsduan1998@163.com>
Date: Wed, 28 Jul 2021 14:47:26 +0800
Subject: [PATCH] =?UTF-8?q?0941.=E6=9C=89=E6=95=88=E7=9A=84=E5=B1=B1?=
 =?UTF-8?q?=E8=84=89=E6=95=B0=E7=BB=84=20=E6=B7=BB=E5=8A=A0Java=E7=89=88?=
 =?UTF-8?q?=E6=9C=AC?=
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---
 problems/0941.有效的山脉数组.md | 31 ++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/problems/0941.有效的山脉数组.md b/problems/0941.有效的山脉数组.md
index 6dbc3da2..167cfb1a 100644
--- a/problems/0941.有效的山脉数组.md
+++ b/problems/0941.有效的山脉数组.md
@@ -18,7 +18,7 @@ https://leetcode-cn.com/problems/valid-mountain-array/
 
 C++代码如下：
 
-```
+```c++
 class Solution {
 public:
     bool validMountainArray(vector<int>& A) {
@@ -38,6 +38,33 @@ public:
     }
 };
 ```
+Java 版本如下：
+
+```java
+class Solution {
+    public boolean validMountainArray(int[] arr) {
+        if (arr.length < 3) { // 此时，一定不是有效的山脉数组
+            return false;
+        }
+        // 双指针
+        int left = 0;
+        int right = arr.length - 1;
+        // 注意防止指针越界
+        while (left + 1 < arr.length && arr[left] < arr[left + 1]) {
+            left++;
+        }
+        // 注意防止指针越界
+        while (right > 0 && arr[right] < arr[right - 1]) {
+            right--;
+        }
+        // 如果left或者right都在起始位置，说明不是山峰
+        if (left == right && left != 0 && right != arr.length - 1) {
+            return true;
+        }
+        return false;
+    }
+}
+```
+
 如果想系统学一学双指针的话， 可以看一下这篇[双指针法：总结篇！](https://mp.weixin.qq.com/s/_p7grwjISfMh0U65uOyCjA)
 
-