From 6aa102ed744836d2053da3e5bb13c0f1c5b56482 Mon Sep 17 00:00:00 2001
From: ironartisan <ironerhalo@gmail.com>
Date: Sun, 15 Aug 2021 22:26:57 +0800
Subject: [PATCH 1/2] =?UTF-8?q?=E6=B7=BB=E5=8A=A00042.=E6=8E=A5=E9=9B=A8?=
 =?UTF-8?q?=E6=B0=B4java=E5=8F=8C=E6=8C=87=E9=92=88=E8=A7=A3=E6=B3=95?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 problems/0042.接雨水.md | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/problems/0042.接雨水.md b/problems/0042.接雨水.md
index 235776a0..b3ee84fd 100644
--- a/problems/0042.接雨水.md
+++ b/problems/0042.接雨水.md
@@ -365,7 +365,31 @@ public:
 ## 其他语言版本 
 
 Java: 
+双指针法
+```java
+class Solution {
+    public int trap(int[] height) {
+        int sum = 0;
+        for (int i = 0; i < height.length; i++) {
+            // 第一个柱子和最后一个柱子不接雨水
+            if (i==0 || i== height.length - 1) continue;
+            
+            int rHeight = height[i]; // 记录右边柱子的最高高度
+            int lHeight = height[i]; // 记录左边柱子的最高高度
+            for (int r = i+1; r < height.length; r++) {
+                if (height[r] > rHeight) rHeight = height[r];
+            }
+            for (int l = i-1; l >= 0; l--) {
+                if(height[l] > lHeight) lHeight = height[l];
+            }
+            int h = Math.min(lHeight, rHeight) - height[i];
+            if (h > 0) sum += h;
+        }
+        return sum;
 
+    }
+}
+```
 Python:
 
 双指针法

From 2405f03d94320d195c97e9719853297d5373aeaf Mon Sep 17 00:00:00 2001
From: ironartisan <ironerhalo@gmail.com>
Date: Tue, 17 Aug 2021 11:21:23 +0800
Subject: [PATCH 2/2] =?UTF-8?q?=E6=B7=BB=E5=8A=A00042.=E6=8E=A5=E9=9B=A8?=
 =?UTF-8?q?=E6=B0=B4java=E5=8A=A8=E6=80=81=E8=A7=84=E5=88=92=E8=A7=A3?=
 =?UTF-8?q?=E6=B3=95?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 problems/0042.接雨水.md | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/problems/0042.接雨水.md b/problems/0042.接雨水.md
index c241b441..22c8c0ef 100644
--- a/problems/0042.接雨水.md
+++ b/problems/0042.接雨水.md
@@ -365,6 +365,7 @@ public:
 ## 其他语言版本 
 
 Java: 
+
 双指针法
 ```java
 class Solution {
@@ -390,6 +391,33 @@ class Solution {
     }
 }
 ```
+动态规划法
+```java
+class Solution {
+    public int trap(int[] height) {
+        int length = height.length;
+        if (length <= 2) return 0;
+        int[] maxLeft = new int[length];
+        int[] maxRight = new int[length];
+        
+        // 记录每个柱子左边柱子最大高度
+        maxLeft[0] = height[0];
+        for (int i = 1; i< length; i++) maxLeft[i] = Math.max(height[i], maxLeft[i-1]);
+        
+        // 记录每个柱子右边柱子最大高度
+        maxRight[length - 1] = height[length - 1];
+        for(int i = length - 2; i >= 0; i--) maxRight[i] = Math.max(height[i], maxRight[i+1]);
+        
+        // 求和
+        int sum = 0;
+        for (int i = 0; i < length; i++) {
+            int count = Math.min(maxLeft[i], maxRight[i]) - height[i];
+            if (count > 0) sum += count;
+        }
+        return sum;
+    }
+}
+```
 Python:
 
 双指针法