Create Flatten-Binary-Tree-to-Linked-List.py

Author: AG-Systems

Leetcode/Flatten-Binary-Tree-to-Linked-List.py

@@ -0,0 +1,31 @@
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution:
+    def flatten(self, root: TreeNode) -> None:
+        """
+        Do not return anything, modify root in-place instead.
+        """
+        if root == None:
+            return None
+        
+        self.dfs_list = []
+        
+        def dfs(root):
+            if root:
+                self.dfs_list.append(root)
+                dfs(root.left)
+                dfs(root.right)
+        
+        dfs(root)
+        root = self.dfs_list.pop(0)
+        while self.dfs_list:
+            node = self.dfs_list.pop(0)
+            root.right = node
+            root.left = None
+            root = root.right
+        return root