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0114-flatten-binary-tree-to-linked-list/0114-flatten-binary-tree-to-linked-list.py

@@ -0,0 +1,35 @@
+# 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
+class Solution:
+    def flatten(self, root: Optional[TreeNode]) -> None:
+        """
+        Do not return anything, modify root in-place instead.
+        """
+        def flattenRecur(r: Optional[TreeNode]) -> (Optional[TreeNode], Optional[TreeNode]):
+            if (r is None or (r.left is None and r.right is None)):
+                rValStr = r.val if r is not None else "None"
+                print(f"{rValStr} -> ({rValStr}, {rValStr})")
+                return (r, r)
+            
+            leftFlat = flattenRecur(r.left)
+            rightFlat = flattenRecur(r.right)
+
+            r.left = None
+
+            if leftFlat[0] is None:
+                r.right = rightFlat[0]
+            else:
+                r.right = leftFlat[0]
+                leftFlat[1].right = rightFlat[0]
+
+            end = rightFlat[1] if rightFlat[1] is not None else leftFlat[1]
+
+            rtValStr = end.val if end is not None else "None"
+            print(f"{r.val} -> ({r.val}, {rtValStr})")
+            return (r, end)
+
+        flattenRecur(root)