Merge branch 'master' into patch-21

problems/0617.合并二叉树.md

@@ -256,23 +256,23 @@ public:
 
 
 Java：
+
 ```Java
 class Solution {
     // 递归
     public TreeNode mergeTrees(TreeNode root1, TreeNode root2) {
-        if (root1 == null) {
-            return root2;
-        }
-        if (root2 == null) {
-            return root1;
-        }
-        root1.val += root2.val;
-        root1.left = mergeTrees(root1.left, root2.left);
-        root1.right = mergeTrees(root1.right, root2.right);
-        return root1;
+        if (root1 == null) return root2;
+        if (root2 == null) return root1;
+
+        TreeNode newRoot = new TreeNode(root1.val + root2.val);
+        newRoot.left = mergeTrees(root1.left,root2.left);
+        newRoot.right = mergeTrees(root1.right,root2.right);
+        return newRoot;
     }
 }
+```
 
+```Java
 class Solution {
    // 迭代
     public TreeNode mergeTrees(TreeNode root1, TreeNode root2) {
@@ -323,4 +323,4 @@ Go：
 * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)
 * B站视频：[代码随想录](https://space.bilibili.com/525438321)
 * 知识星球：[代码随想录](https://mp.weixin.qq.com/s/QVF6upVMSbgvZy8lHZS3CQ)
-<div align="center"><img src=../pics/公众号.png width=450 alt=> </img></div>
+<div align="center"><img src=../pics/公众号.png width=450 alt=> </img></div>