Merge pull request #149 from jojoo15/patch-2

添加 0257.二叉树的所有路径 python版本

problems/0257.二叉树的所有路径.md

@@ -324,8 +324,31 @@ class Solution {
 ```
 
 Python：
+```Python
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+class Solution:
+    def binaryTreePaths(self, root: TreeNode) -> List[str]:
+        path=[]
+        res=[]
+        def backtrace(root, path):
+            if not root:return 
+            path.append(root.val)
+            if (not root.left)and (not root.right):
+               res.append(path[:])
+            ways=[]
+            if root.left:ways.append(root.left)
+            if root.right:ways.append(root.right)
+            for way in ways:
+                backtrace(way,path)
+                path.pop()
+        backtrace(root,path)
+        return ["->".join(list(map(str,i))) for i in res]
 
-
+```
 Go：