Flatten binary tree to linked list solution

Author: joshguha

113_flatten_binary_tree_to_linked_list.py

@@ -0,0 +1,51 @@
+# Definition for a binary tree node.
+# class TreeNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution(object):
+    # stack
+    def flatten(self, root):
+        """
+        :type root: TreeNode
+        :rtype: void Do not return anything, modify root in-place instead.
+        """
+        if root is None:
+            return
+        if root.left is None and root.right is None:
+            return
+        current = root
+        stack = [root]
+        while stack:
+            node = stack.pop()
+            self.appendNode(stack, node.right)
+            self.appendNode(stack, node.left)
+            if current != node:
+                current.right = node
+                current.left = None
+                current = node
+
+    def appendNode(self, stack, node):
+        if node:
+            stack.append(node)
+
+    # recursive
+    # https://discuss.leetcode.com/topic/11444/my-short-post-order-traversal-java-solution-for-share/2
+    # def __init__(self):
+    #     self.prev = None
+    #
+    # def flatten(self, root):
+    #     if root is None:
+    #         return
+    #     self.flatten(root.right)
+    #     self.flatten(root.left)
+    #     root.right = self.prev
+    #     root.left = None
+    #     self.prev = root
+
+
+
+
+