From fc2dc45a198f9562fcbefdb399d71482c8c45cd8 Mon Sep 17 00:00:00 2001
From: NevS <1173325467@qq.com>
Date: Thu, 24 Jun 2021 21:41:10 +0800
Subject: [PATCH 1/2] =?UTF-8?q?=E5=A2=9E=E5=8A=A0=200617.=E5=90=88?=
 =?UTF-8?q?=E5=B9=B6=E4=BA=8C=E5=8F=89=E6=A0=91=20go=E7=89=88=20=EF=BC=88?=
 =?UTF-8?q?=E5=A2=9E=E5=8A=A0=E5=89=8D=E5=BA=8F=E9=81=8D=E5=8E=86=E7=AE=80?=
 =?UTF-8?q?=E6=B4=81=E7=89=88=E8=A7=A3=E9=A2=98=EF=BC=89?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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增加前序遍历简洁版解题
---
 problems/0617.合并二叉树.md | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/problems/0617.合并二叉树.md b/problems/0617.合并二叉树.md
index 2ff093a3..f325df64 100644
--- a/problems/0617.合并二叉树.md
+++ b/problems/0617.合并二叉树.md
@@ -368,6 +368,20 @@ func mergeTrees(t1 *TreeNode, t2 *TreeNode) *TreeNode {
         Right: mergeTrees(t1.Right,t2.Right)}
     return root
 }
+
+// 前序遍历简洁版
+func mergeTrees(root1 *TreeNode, root2 *TreeNode) *TreeNode {
+    if root1 == nil {
+        return root2
+    }
+    if root2 == nil {
+        return root1
+    }
+    root1.Val += root2.Val
+    root1.Left = mergeTrees(root1.Left, root2.Left)
+    root1.Right = mergeTrees(root1.Right, root2.Right)
+    return root1
+}
 ```
 
 JavaScript:

From 24e7994d2708b90f304dd424f0175bcce845955f Mon Sep 17 00:00:00 2001
From: Jijie LIU <liujijieseason@gmail.com>
Date: Thu, 24 Jun 2021 20:29:02 +0200
Subject: [PATCH 2/2] =?UTF-8?q?update=2063.=20=E4=B8=8D=E5=90=8C=E8=B7=AF?=
 =?UTF-8?q?=E5=BE=84=20II=EF=BC=9A=E6=8F=90=E4=BE=9B=E4=B8=80=E7=BB=B4dp?=
 =?UTF-8?q?=E6=95=B0=E7=BB=84=E7=9A=84Python=E8=A7=A3=E6=B3=95?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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---
 problems/0063.不同路径II.md | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/problems/0063.不同路径II.md b/problems/0063.不同路径II.md
index 52f00322..a61ffd02 100644
--- a/problems/0063.不同路径II.md
+++ b/problems/0063.不同路径II.md
@@ -232,6 +232,38 @@ class Solution:
         return dp[-1][-1]
 ```
 
+```python
+class Solution:
+    """
+    使用一维dp数组
+    """
+
+    def uniquePathsWithObstacles(self, obstacleGrid: List[List[int]]) -> int:
+        m, n = len(obstacleGrid), len(obstacleGrid[0])
+
+        # 初始化dp数组
+        # 该数组缓存当前行
+        curr = [0] * n
+        for j in range(n):
+            if obstacleGrid[0][j] == 1:
+                break
+            curr[j] = 1
+            
+        for i in range(1, m): # 从第二行开始
+            for j in range(n): # 从第一列开始，因为第一列可能有障碍物
+                # 有障碍物处无法通行，状态就设成0
+                if obstacleGrid[i][j] == 1:
+                    curr[j] = 0
+                elif j > 0:
+                    # 等价于
+                    # dp[i][j] = dp[i - 1][j] + dp[i][j - 1]
+                    curr[j] = curr[j] + curr[j - 1]
+                # 隐含的状态更新
+                # dp[i][0] = dp[i - 1][0]
+        
+        return curr[n - 1]
+```
+
 
 Go：