Update 0257.二叉树的所有路径.md

problems/0257.二叉树的所有路径.md

@@ -468,6 +468,71 @@ class Solution {
 ```
 ---
 ## Python:  
+	
+	
+递归法+回溯（版本一）
+```Python
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+import copy
+from typing import List, Optional
+
+class Solution:
+    def binaryTreePaths(self, root: Optional[TreeNode]) -> List[str]:
+        if not root:
+            return []
+        result = []
+        self.generate_paths(root, [], result)
+        return result
+    
+    def generate_paths(self, node: TreeNode, path: List[int], result: List[str]) -> None:
+        path.append(node.val)
+        if not node.left and not node.right:
+            result.append('->'.join(map(str, path)))
+        if node.left:
+            self.generate_paths(node.left, copy.copy(path), result)
+        if node.right:
+            self.generate_paths(node.right, copy.copy(path), result)
+        path.pop()
+
+
+```
+递归法+回溯（版本二）
+```Python
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+import copy
+from typing import List, Optional
+
+class Solution:
+    def binaryTreePaths(self, root: Optional[TreeNode]) -> List[str]:
+        if not root:
+            return []
+        result = []
+        self.generate_paths(root, [], result)
+        return result
+    
+    def generate_paths(self, node: TreeNode, path: List[int], result: List[str]) -> None:
+        if not node:
+            return
+        path.append(node.val)
+        if not node.left and not node.right:
+            result.append('->'.join(map(str, path)))
+        else:
+            self.generate_paths(node.left, copy.copy(path), result)
+            self.generate_paths(node.right, copy.copy(path), result)
+        path.pop()
+
+```
+	
 递归法+隐形回溯
 ```Python
 # Definition for a binary tree node.