Merge pull request youngyangyang04#2522 from skylarkkk/master

Update 二叉树的递归遍历.md python代码少了关键一句

Author: youngyangyang04

problems/二叉树的递归遍历.md

@@ -189,7 +189,6 @@ class Solution:
             res.append(node.val)
             dfs(node.left)
             dfs(node.right)
-
         dfs(root)
         return res
 
@@ -207,7 +206,6 @@ class Solution:
             dfs(node.left)
             res.append(node.val)
             dfs(node.right)
-            
         dfs(root)
         return res
 ```