diff --git "a/problems/344円272円214円345円217円211円346円240円221円347円232円204円351円200円222円345円275円222円351円201円215円345円216円206円.md" "b/problems/344円272円214円345円217円211円346円240円221円347円232円204円351円200円222円345円275円222円351円201円215円345円216円206円.md"
index edd55aad3c..4621d4a739 100644
--- "a/problems/344円272円214円345円217円211円346円240円221円347円232円204円351円200円222円345円275円222円351円201円215円345円216円206円.md"
+++ "b/problems/344円272円214円345円217円211円346円240円221円347円232円204円351円200円222円345円275円222円351円201円215円345円216円206円.md"
@@ -180,26 +180,34 @@ class Solution {
 
 class Solution:
 def preorderTraversal(self, root: TreeNode) -> List[int]:
- if not root:
- return []
-
- left = self.preorderTraversal(root.left)
- right = self.preorderTraversal(root.right)
-
- return [root.val] + left + right
+ res = []
+ 
+ def dfs(node):
+ if node is None:
+ return
+ 
+ res.append(node.val)
+ dfs(node.left)
+ dfs(node.right)
+ 
+ return res
 
 ```
 ```python
 # 中序遍历-递归-LC94_二叉树的中序遍历
 class Solution:
 def inorderTraversal(self, root: TreeNode) -> List[int]:
- if root is None:
- return []
-
- left = self.inorderTraversal(root.left)
- right = self.inorderTraversal(root.right)
-
- return left + [root.val] + right
+ res = []
+ 
+ def dfs(node):
+ if node is None:
+ return
+ 
+ dfs(node.left)
+ res.append(node.val)
+ dfs(node.right)
+ 
+ return res
 ```
 ```python
 
@@ -207,13 +215,17 @@ class Solution:
 # 后序遍历-递归-LC145_二叉树的后序遍历
 class Solution:
 def postorderTraversal(self, root: TreeNode) -> List[int]:
- if not root:
- return []
-
- left = self.postorderTraversal(root.left)
- right = self.postorderTraversal(root.right)
-
- return left + right + [root.val]
+ res = []
+ 
+ def dfs(node):
+ if node is None:
+ return
+ 
+ dfs(node.left)
+ dfs(node.right)
+ res.append(node.val)
+ 
+ return res
 ```
 
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