Arunsiva003 patch 1 flatten tree

data_structures/binary_tree/flatten_binarytree_to_linkedlist.py

@@ -0,0 +1,138 @@
+"""
+Binary Tree Flattening Algorithm
+
+This code defines an algorithm to flatten a binary tree into a linked list
+represented using the right pointers of the tree nodes. It uses in-place
+flattening and demonstrates the flattening process along with a display
+function to visualize the flattened linked list.
+https://www.geeksforgeeks.org/flatten-a-binary-tree-into-linked-list
+
+Author: Arunkumar A
+Date: 04/09/2023
+"""
+from __future__ import annotations
+
+
+class TreeNode:
+ """
+ A TreeNode has data variable and pointers to TreeNode objects
+ for its left and right children.
+ """
+
+ def __init__(self, data: int) -> None:
+ self.data = data
+ self.left: TreeNode | None = None
+ self.right: TreeNode | None = None
+
+
+def build_tree() -> TreeNode:
+ """
+ Build and return a sample binary tree.
+
+ Returns:
+ TreeNode: The root of the binary tree.
+
+ Examples:
+ >>> root = build_tree()
+ >>> root.data
+ 1
+ >>> root.left.data
+ 2
+ >>> root.right.data
+ 5
+ >>> root.left.left.data
+ 3
+ >>> root.left.right.data
+ 4
+ >>> root.right.right.data
+ 6
+ """
+ root = TreeNode(1)
+ root.left = TreeNode(2)
+ root.right = TreeNode(5)
+ root.left.left = TreeNode(3)
+ root.left.right = TreeNode(4)
+ root.right.right = TreeNode(6)
+ return root
+
+
+def flatten(root: TreeNode | None) -> None:
+ """
+ Flatten a binary tree into a linked list in-place, where the linked list is
+ represented using the right pointers of the tree nodes.
+
+ Args:
+ root (TreeNode): The root of the binary tree to be flattened.
+
+ Examples:
+ >>> root = TreeNode(1)
+ >>> root.left = TreeNode(2)
+ >>> root.right = TreeNode(5)
+ >>> root.left.left = TreeNode(3)
+ >>> root.left.right = TreeNode(4)
+ >>> root.right.right = TreeNode(6)
+ >>> flatten(root)
+ >>> root.data
+ 1
+ >>> root.right.right is None
+ False
+ >>> root.right.right = TreeNode(3)
+ >>> root.right.right.right is None
+ True
+ """
+ if not root:
+ return
+
+ # Flatten the left subtree
+ flatten(root.left)
+
+ # Save the right subtree
+ right_subtree = root.right
+
+ # Make the left subtree the new right subtree
+ root.right = root.left
+ root.left = None
+
+ # Find the end of the new right subtree
+ current = root
+ while current.right:
+ current = current.right
+
+ # Append the original right subtree to the end
+ current.right = right_subtree
+
+ # Flatten the updated right subtree
+ flatten(right_subtree)
+
+
+def display_linked_list(root: TreeNode | None) -> None:
+ """
+ Display the flattened linked list.
+
+ Args:
+ root (TreeNode | None): The root of the flattened linked list.
+
+ Examples:
+ >>> root = TreeNode(1)
+ >>> root.right = TreeNode(2)
+ >>> root.right.right = TreeNode(3)
+ >>> display_linked_list(root)
+ 1 2 3
+ >>> root = None
+ >>> display_linked_list(root)
+
+ """
+ current = root
+ while current:
+ if current.right is None:
+ print(current.data, end="")
+ break
+ print(current.data, end=" ")
+ current = current.right
+
+
+if __name__ == "__main__":
+ print("Flattened Linked List:")
+ root = build_tree()
+ flatten(root)
+ display_linked_list(root)

data_structures/binary_tree/flatten_binarytree_to_linkedlist.py

@@ -0,0 +1,138 @@
+"""
+Binary Tree Flattening Algorithm
+
+This code defines an algorithm to flatten a binary tree into a linked list
+represented using the right pointers of the tree nodes. It uses in-place
+flattening and demonstrates the flattening process along with a display
+function to visualize the flattened linked list.
+https://www.geeksforgeeks.org/flatten-a-binary-tree-into-linked-list
+
+Author: Arunkumar A
+Date: 04/09/2023
+"""
+from __future__ import annotations
+
+
+class TreeNode:
+ """
+ A TreeNode has data variable and pointers to TreeNode objects
+ for its left and right children.
+ """
+
+ def __init__(self, data: int) -> None:
+ self.data = data
+ self.left: TreeNode | None = None
+ self.right: TreeNode | None = None
+
+
+def build_tree() -> TreeNode:
+ """
+ Build and return a sample binary tree.
+
+ Returns:
+ TreeNode: The root of the binary tree.
+
+ Examples:
+ >>> root = build_tree()
+ >>> root.data
+ 1
+ >>> root.left.data
+ 2
+ >>> root.right.data
+ 5
+ >>> root.left.left.data
+ 3
+ >>> root.left.right.data
+ 4
+ >>> root.right.right.data
+ 6
+ """
+ root = TreeNode(1)
+ root.left = TreeNode(2)
+ root.right = TreeNode(5)
+ root.left.left = TreeNode(3)
+ root.left.right = TreeNode(4)
+ root.right.right = TreeNode(6)
+ return root
+
+
+def flatten(root: TreeNode | None) -> None:
+ """
+ Flatten a binary tree into a linked list in-place, where the linked list is
+ represented using the right pointers of the tree nodes.
+
+ Args:
+ root (TreeNode): The root of the binary tree to be flattened.
+
+ Examples:
+ >>> root = TreeNode(1)
+ >>> root.left = TreeNode(2)
+ >>> root.right = TreeNode(5)
+ >>> root.left.left = TreeNode(3)
+ >>> root.left.right = TreeNode(4)
+ >>> root.right.right = TreeNode(6)
+ >>> flatten(root)
+ >>> root.data
+ 1
+ >>> root.right.right is None
+ False
+ >>> root.right.right = TreeNode(3)
+ >>> root.right.right.right is None
+ True
+ """
+ if not root:
+ return
+
+ # Flatten the left subtree
+ flatten(root.left)
+
+ # Save the right subtree
+ right_subtree = root.right
+
+ # Make the left subtree the new right subtree
+ root.right = root.left
+ root.left = None
+
+ # Find the end of the new right subtree
+ current = root
+ while current.right:
+ current = current.right
+
+ # Append the original right subtree to the end
+ current.right = right_subtree
+
+ # Flatten the updated right subtree
+ flatten(right_subtree)
+
+
+def display_linked_list(root: TreeNode | None) -> None:
+ """
+ Display the flattened linked list.
+
+ Args:
+ root (TreeNode | None): The root of the flattened linked list.
+
+ Examples:
+ >>> root = TreeNode(1)
+ >>> root.right = TreeNode(2)
+ >>> root.right.right = TreeNode(3)
+ >>> display_linked_list(root)
+ 1 2 3
+ >>> root = None
+ >>> display_linked_list(root)
+
+ """
+ current = root
+ while current:
+ if current.right is None:
+ print(current.data, end="")
+ break
+ print(current.data, end=" ")
+ current = current.right
+
+
+if __name__ == "__main__":
+ print("Flattened Linked List:")
+ root = build_tree()
+ flatten(root)
+ display_linked_list(root)

data_structures/binary_tree/flatten_binarytree_to_linkedlist.py

@@ -0,0 +1,138 @@
+"""
+Binary Tree Flattening Algorithm
+
+This code defines an algorithm to flatten a binary tree into a linked list
+represented using the right pointers of the tree nodes. It uses in-place
+flattening and demonstrates the flattening process along with a display
+function to visualize the flattened linked list.
+https://www.geeksforgeeks.org/flatten-a-binary-tree-into-linked-list
+
+Author: Arunkumar A
+Date: 04/09/2023
+"""
+from __future__ import annotations
+
+
+class TreeNode:
+ """
+ A TreeNode has data variable and pointers to TreeNode objects
+ for its left and right children.
+ """
+
+ def __init__(self, data: int) -> None:
+ self.data = data
+ self.left: TreeNode | None = None
+ self.right: TreeNode | None = None
+
+
+def build_tree() -> TreeNode:
+ """
+ Build and return a sample binary tree.
+
+ Returns:
+ TreeNode: The root of the binary tree.
+
+ Examples:
+ >>> root = build_tree()
+ >>> root.data
+ 1
+ >>> root.left.data
+ 2
+ >>> root.right.data
+ 5
+ >>> root.left.left.data
+ 3
+ >>> root.left.right.data
+ 4
+ >>> root.right.right.data
+ 6
+ """
+ root = TreeNode(1)
+ root.left = TreeNode(2)
+ root.right = TreeNode(5)
+ root.left.left = TreeNode(3)
+ root.left.right = TreeNode(4)
+ root.right.right = TreeNode(6)
+ return root
+
+
+def flatten(root: TreeNode | None) -> None:
+ """
+ Flatten a binary tree into a linked list in-place, where the linked list is
+ represented using the right pointers of the tree nodes.
+
+ Args:
+ root (TreeNode): The root of the binary tree to be flattened.
+
+ Examples:
+ >>> root = TreeNode(1)
+ >>> root.left = TreeNode(2)
+ >>> root.right = TreeNode(5)
+ >>> root.left.left = TreeNode(3)
+ >>> root.left.right = TreeNode(4)
+ >>> root.right.right = TreeNode(6)
+ >>> flatten(root)
+ >>> root.data
+ 1
+ >>> root.right.right is None
+ False
+ >>> root.right.right = TreeNode(3)
+ >>> root.right.right.right is None
+ True
+ """
+ if not root:
+ return
+
+ # Flatten the left subtree
+ flatten(root.left)
+
+ # Save the right subtree
+ right_subtree = root.right
+
+ # Make the left subtree the new right subtree
+ root.right = root.left
+ root.left = None
+
+ # Find the end of the new right subtree
+ current = root
+ while current.right:
+ current = current.right
+
+ # Append the original right subtree to the end
+ current.right = right_subtree
+
+ # Flatten the updated right subtree
+ flatten(right_subtree)
+
+
+def display_linked_list(root: TreeNode | None) -> None:
+ """
+ Display the flattened linked list.
+
+ Args:
+ root (TreeNode | None): The root of the flattened linked list.
+
+ Examples:
+ >>> root = TreeNode(1)
+ >>> root.right = TreeNode(2)
+ >>> root.right.right = TreeNode(3)
+ >>> display_linked_list(root)
+ 1 2 3
+ >>> root = None
+ >>> display_linked_list(root)
+
+ """
+ current = root
+ while current:
+ if current.right is None:
+ print(current.data, end="")
+ break
+ print(current.data, end=" ")
+ current = current.right
+
+
+if __name__ == "__main__":
+ print("Flattened Linked List:")
+ root = build_tree()
+ flatten(root)
+ display_linked_list(root)

data_structures/binary_tree/flatten_binarytree_to_linkedlist.py

@@ -0,0 +1,138 @@
+"""
+Binary Tree Flattening Algorithm
+
+This code defines an algorithm to flatten a binary tree into a linked list
+represented using the right pointers of the tree nodes. It uses in-place
+flattening and demonstrates the flattening process along with a display
+function to visualize the flattened linked list.
+https://www.geeksforgeeks.org/flatten-a-binary-tree-into-linked-list
+
+Author: Arunkumar A
+Date: 04/09/2023
+"""
+from __future__ import annotations
+
+
+class TreeNode:
+ """
+ A TreeNode has data variable and pointers to TreeNode objects
+ for its left and right children.
+ """
+
+ def __init__(self, data: int) -> None:
+ self.data = data
+ self.left: TreeNode | None = None
+ self.right: TreeNode | None = None
+
+
+def build_tree() -> TreeNode:
+ """
+ Build and return a sample binary tree.
+
+ Returns:
+ TreeNode: The root of the binary tree.
+
+ Examples:
+ >>> root = build_tree()
+ >>> root.data
+ 1
+ >>> root.left.data
+ 2
+ >>> root.right.data
+ 5
+ >>> root.left.left.data
+ 3
+ >>> root.left.right.data
+ 4
+ >>> root.right.right.data
+ 6
+ """
+ root = TreeNode(1)
+ root.left = TreeNode(2)
+ root.right = TreeNode(5)
+ root.left.left = TreeNode(3)
+ root.left.right = TreeNode(4)
+ root.right.right = TreeNode(6)
+ return root
+
+
+def flatten(root: TreeNode | None) -> None:
+ """
+ Flatten a binary tree into a linked list in-place, where the linked list is
+ represented using the right pointers of the tree nodes.
+
+ Args:
+ root (TreeNode): The root of the binary tree to be flattened.
+
+ Examples:
+ >>> root = TreeNode(1)
+ >>> root.left = TreeNode(2)
+ >>> root.right = TreeNode(5)
+ >>> root.left.left = TreeNode(3)
+ >>> root.left.right = TreeNode(4)
+ >>> root.right.right = TreeNode(6)
+ >>> flatten(root)
+ >>> root.data
+ 1
+ >>> root.right.right is None
+ False
+ >>> root.right.right = TreeNode(3)
+ >>> root.right.right.right is None
+ True
+ """
+ if not root:
+ return
+
+ # Flatten the left subtree
+ flatten(root.left)
+
+ # Save the right subtree
+ right_subtree = root.right
+
+ # Make the left subtree the new right subtree
+ root.right = root.left
+ root.left = None
+
+ # Find the end of the new right subtree
+ current = root
+ while current.right:
+ current = current.right
+
+ # Append the original right subtree to the end
+ current.right = right_subtree
+
+ # Flatten the updated right subtree
+ flatten(right_subtree)
+
+
+def display_linked_list(root: TreeNode | None) -> None:
+ """
+ Display the flattened linked list.
+
+ Args:
+ root (TreeNode | None): The root of the flattened linked list.
+
+ Examples:
+ >>> root = TreeNode(1)
+ >>> root.right = TreeNode(2)
+ >>> root.right.right = TreeNode(3)
+ >>> display_linked_list(root)
+ 1 2 3
+ >>> root = None
+ >>> display_linked_list(root)
+
+ """
+ current = root
+ while current:
+ if current.right is None:
+ print(current.data, end="")
+ break
+ print(current.data, end=" ")
+ current = current.right
+
+
+if __name__ == "__main__":
+ print("Flattened Linked List:")
+ root = build_tree()
+ flatten(root)
+ display_linked_list(root)

data_structures/binary_tree/flatten_binarytree_to_linkedlist.py

@@ -0,0 +1,138 @@
+"""
+Binary Tree Flattening Algorithm
+
+This code defines an algorithm to flatten a binary tree into a linked list
+represented using the right pointers of the tree nodes. It uses in-place
+flattening and demonstrates the flattening process along with a display
+function to visualize the flattened linked list.
+https://www.geeksforgeeks.org/flatten-a-binary-tree-into-linked-list
+
+Author: Arunkumar A
+Date: 04/09/2023
+"""
+from __future__ import annotations
+
+
+class TreeNode:
+ """
+ A TreeNode has data variable and pointers to TreeNode objects
+ for its left and right children.
+ """
+
+ def __init__(self, data: int) -> None:
+ self.data = data
+ self.left: TreeNode | None = None
+ self.right: TreeNode | None = None
+
+
+def build_tree() -> TreeNode:
+ """
+ Build and return a sample binary tree.
+
+ Returns:
+ TreeNode: The root of the binary tree.
+
+ Examples:
+ >>> root = build_tree()
+ >>> root.data
+ 1
+ >>> root.left.data
+ 2
+ >>> root.right.data
+ 5
+ >>> root.left.left.data
+ 3
+ >>> root.left.right.data
+ 4
+ >>> root.right.right.data
+ 6
+ """
+ root = TreeNode(1)
+ root.left = TreeNode(2)
+ root.right = TreeNode(5)
+ root.left.left = TreeNode(3)
+ root.left.right = TreeNode(4)
+ root.right.right = TreeNode(6)
+ return root
+
+
+def flatten(root: TreeNode | None) -> None:
+ """
+ Flatten a binary tree into a linked list in-place, where the linked list is
+ represented using the right pointers of the tree nodes.
+
+ Args:
+ root (TreeNode): The root of the binary tree to be flattened.
+
+ Examples:
+ >>> root = TreeNode(1)
+ >>> root.left = TreeNode(2)
+ >>> root.right = TreeNode(5)
+ >>> root.left.left = TreeNode(3)
+ >>> root.left.right = TreeNode(4)
+ >>> root.right.right = TreeNode(6)
+ >>> flatten(root)
+ >>> root.data
+ 1
+ >>> root.right.right is None
+ False
+ >>> root.right.right = TreeNode(3)
+ >>> root.right.right.right is None
+ True
+ """
+ if not root:
+ return
+
+ # Flatten the left subtree
+ flatten(root.left)
+
+ # Save the right subtree
+ right_subtree = root.right
+
+ # Make the left subtree the new right subtree
+ root.right = root.left
+ root.left = None
+
+ # Find the end of the new right subtree
+ current = root
+ while current.right:
+ current = current.right
+
+ # Append the original right subtree to the end
+ current.right = right_subtree
+
+ # Flatten the updated right subtree
+ flatten(right_subtree)
+
+
+def display_linked_list(root: TreeNode | None) -> None:
+ """
+ Display the flattened linked list.
+
+ Args:
+ root (TreeNode | None): The root of the flattened linked list.
+
+ Examples:
+ >>> root = TreeNode(1)
+ >>> root.right = TreeNode(2)
+ >>> root.right.right = TreeNode(3)
+ >>> display_linked_list(root)
+ 1 2 3
+ >>> root = None
+ >>> display_linked_list(root)
+
+ """
+ current = root
+ while current:
+ if current.right is None:
+ print(current.data, end="")
+ break
+ print(current.data, end=" ")
+ current = current.right
+
+
+if __name__ == "__main__":
+ print("Flattened Linked List:")
+ root = build_tree()
+ flatten(root)
+ display_linked_list(root)

data_structures/binary_tree/flatten_binarytree_to_linkedlist.py

@@ -0,0 +1,138 @@
+"""
+Binary Tree Flattening Algorithm
+
+This code defines an algorithm to flatten a binary tree into a linked list
+represented using the right pointers of the tree nodes. It uses in-place
+flattening and demonstrates the flattening process along with a display
+function to visualize the flattened linked list.
+https://www.geeksforgeeks.org/flatten-a-binary-tree-into-linked-list
+
+Author: Arunkumar A
+Date: 04/09/2023
+"""
+from __future__ import annotations
+
+
+class TreeNode:
+ """
+ A TreeNode has data variable and pointers to TreeNode objects
+ for its left and right children.
+ """
+
+ def __init__(self, data: int) -> None:
+ self.data = data
+ self.left: TreeNode | None = None
+ self.right: TreeNode | None = None
+
+
+def build_tree() -> TreeNode:
+ """
+ Build and return a sample binary tree.
+
+ Returns:
+ TreeNode: The root of the binary tree.
+
+ Examples:
+ >>> root = build_tree()
+ >>> root.data
+ 1
+ >>> root.left.data
+ 2
+ >>> root.right.data
+ 5
+ >>> root.left.left.data
+ 3
+ >>> root.left.right.data
+ 4
+ >>> root.right.right.data
+ 6
+ """
+ root = TreeNode(1)
+ root.left = TreeNode(2)
+ root.right = TreeNode(5)
+ root.left.left = TreeNode(3)
+ root.left.right = TreeNode(4)
+ root.right.right = TreeNode(6)
+ return root
+
+
+def flatten(root: TreeNode | None) -> None:
+ """
+ Flatten a binary tree into a linked list in-place, where the linked list is
+ represented using the right pointers of the tree nodes.
+
+ Args:
+ root (TreeNode): The root of the binary tree to be flattened.
+
+ Examples:
+ >>> root = TreeNode(1)
+ >>> root.left = TreeNode(2)
+ >>> root.right = TreeNode(5)
+ >>> root.left.left = TreeNode(3)
+ >>> root.left.right = TreeNode(4)
+ >>> root.right.right = TreeNode(6)
+ >>> flatten(root)
+ >>> root.data
+ 1
+ >>> root.right.right is None
+ False
+ >>> root.right.right = TreeNode(3)
+ >>> root.right.right.right is None
+ True
+ """
+ if not root:
+ return
+
+ # Flatten the left subtree
+ flatten(root.left)
+
+ # Save the right subtree
+ right_subtree = root.right
+
+ # Make the left subtree the new right subtree
+ root.right = root.left
+ root.left = None
+
+ # Find the end of the new right subtree
+ current = root
+ while current.right:
+ current = current.right
+
+ # Append the original right subtree to the end
+ current.right = right_subtree
+
+ # Flatten the updated right subtree
+ flatten(right_subtree)
+
+
+def display_linked_list(root: TreeNode | None) -> None:
+ """
+ Display the flattened linked list.
+
+ Args:
+ root (TreeNode | None): The root of the flattened linked list.
+
+ Examples:
+ >>> root = TreeNode(1)
+ >>> root.right = TreeNode(2)
+ >>> root.right.right = TreeNode(3)
+ >>> display_linked_list(root)
+ 1 2 3
+ >>> root = None
+ >>> display_linked_list(root)
+
+ """
+ current = root
+ while current:
+ if current.right is None:
+ print(current.data, end="")
+ break
+ print(current.data, end=" ")
+ current = current.right
+
+
+if __name__ == "__main__":
+ print("Flattened Linked List:")
+ root = build_tree()
+ flatten(root)
+ display_linked_list(root)

data_structures/binary_tree/flatten_binarytree_to_linkedlist.py

@@ -0,0 +1,138 @@
+"""
+Binary Tree Flattening Algorithm
+
+This code defines an algorithm to flatten a binary tree into a linked list
+represented using the right pointers of the tree nodes. It uses in-place
+flattening and demonstrates the flattening process along with a display
+function to visualize the flattened linked list.
+https://www.geeksforgeeks.org/flatten-a-binary-tree-into-linked-list
+
+Author: Arunkumar A
+Date: 04/09/2023
+"""
+from __future__ import annotations
+
+
+class TreeNode:
+ """
+ A TreeNode has data variable and pointers to TreeNode objects
+ for its left and right children.
+ """
+
+ def __init__(self, data: int) -> None:
+ self.data = data
+ self.left: TreeNode | None = None
+ self.right: TreeNode | None = None
+
+
+def build_tree() -> TreeNode:
+ """
+ Build and return a sample binary tree.
+
+ Returns:
+ TreeNode: The root of the binary tree.
+
+ Examples:
+ >>> root = build_tree()
+ >>> root.data
+ 1
+ >>> root.left.data
+ 2
+ >>> root.right.data
+ 5
+ >>> root.left.left.data
+ 3
+ >>> root.left.right.data
+ 4
+ >>> root.right.right.data
+ 6
+ """
+ root = TreeNode(1)
+ root.left = TreeNode(2)
+ root.right = TreeNode(5)
+ root.left.left = TreeNode(3)
+ root.left.right = TreeNode(4)
+ root.right.right = TreeNode(6)
+ return root
+
+
+def flatten(root: TreeNode | None) -> None:
+ """
+ Flatten a binary tree into a linked list in-place, where the linked list is
+ represented using the right pointers of the tree nodes.
+
+ Args:
+ root (TreeNode): The root of the binary tree to be flattened.
+
+ Examples:
+ >>> root = TreeNode(1)
+ >>> root.left = TreeNode(2)
+ >>> root.right = TreeNode(5)
+ >>> root.left.left = TreeNode(3)
+ >>> root.left.right = TreeNode(4)
+ >>> root.right.right = TreeNode(6)
+ >>> flatten(root)
+ >>> root.data
+ 1
+ >>> root.right.right is None
+ False
+ >>> root.right.right = TreeNode(3)
+ >>> root.right.right.right is None
+ True
+ """
+ if not root:
+ return
+
+ # Flatten the left subtree
+ flatten(root.left)
+
+ # Save the right subtree
+ right_subtree = root.right
+
+ # Make the left subtree the new right subtree
+ root.right = root.left
+ root.left = None
+
+ # Find the end of the new right subtree
+ current = root
+ while current.right:
+ current = current.right
+
+ # Append the original right subtree to the end
+ current.right = right_subtree
+
+ # Flatten the updated right subtree
+ flatten(right_subtree)
+
+
+def display_linked_list(root: TreeNode | None) -> None:
+ """
+ Display the flattened linked list.
+
+ Args:
+ root (TreeNode | None): The root of the flattened linked list.
+
+ Examples:
+ >>> root = TreeNode(1)
+ >>> root.right = TreeNode(2)
+ >>> root.right.right = TreeNode(3)
+ >>> display_linked_list(root)
+ 1 2 3
+ >>> root = None
+ >>> display_linked_list(root)
+
+ """
+ current = root
+ while current:
+ if current.right is None:
+ print(current.data, end="")
+ break
+ print(current.data, end=" ")
+ current = current.right
+
+
+if __name__ == "__main__":
+ print("Flattened Linked List:")
+ root = build_tree()
+ flatten(root)
+ display_linked_list(root)

data_structures/binary_tree/flatten_binarytree_to_linkedlist.py

@@ -0,0 +1,138 @@
+"""
+Binary Tree Flattening Algorithm
+
+This code defines an algorithm to flatten a binary tree into a linked list
+represented using the right pointers of the tree nodes. It uses in-place
+flattening and demonstrates the flattening process along with a display
+function to visualize the flattened linked list.
+https://www.geeksforgeeks.org/flatten-a-binary-tree-into-linked-list
+
+Author: Arunkumar A
+Date: 04/09/2023
+"""
+from __future__ import annotations
+
+
+class TreeNode:
+ """
+ A TreeNode has data variable and pointers to TreeNode objects
+ for its left and right children.
+ """
+
+ def __init__(self, data: int) -> None:
+ self.data = data
+ self.left: TreeNode | None = None
+ self.right: TreeNode | None = None
+
+
+def build_tree() -> TreeNode:
+ """
+ Build and return a sample binary tree.
+
+ Returns:
+ TreeNode: The root of the binary tree.
+
+ Examples:
+ >>> root = build_tree()
+ >>> root.data
+ 1
+ >>> root.left.data
+ 2
+ >>> root.right.data
+ 5
+ >>> root.left.left.data
+ 3
+ >>> root.left.right.data
+ 4
+ >>> root.right.right.data
+ 6
+ """
+ root = TreeNode(1)
+ root.left = TreeNode(2)
+ root.right = TreeNode(5)
+ root.left.left = TreeNode(3)
+ root.left.right = TreeNode(4)
+ root.right.right = TreeNode(6)
+ return root
+
+
+def flatten(root: TreeNode | None) -> None:
+ """
+ Flatten a binary tree into a linked list in-place, where the linked list is
+ represented using the right pointers of the tree nodes.
+
+ Args:
+ root (TreeNode): The root of the binary tree to be flattened.
+
+ Examples:
+ >>> root = TreeNode(1)
+ >>> root.left = TreeNode(2)
+ >>> root.right = TreeNode(5)
+ >>> root.left.left = TreeNode(3)
+ >>> root.left.right = TreeNode(4)
+ >>> root.right.right = TreeNode(6)
+ >>> flatten(root)
+ >>> root.data
+ 1
+ >>> root.right.right is None
+ False
+ >>> root.right.right = TreeNode(3)
+ >>> root.right.right.right is None
+ True
+ """
+ if not root:
+ return
+
+ # Flatten the left subtree
+ flatten(root.left)
+
+ # Save the right subtree
+ right_subtree = root.right
+
+ # Make the left subtree the new right subtree
+ root.right = root.left
+ root.left = None
+
+ # Find the end of the new right subtree
+ current = root
+ while current.right:
+ current = current.right
+
+ # Append the original right subtree to the end
+ current.right = right_subtree
+
+ # Flatten the updated right subtree
+ flatten(right_subtree)
+
+
+def display_linked_list(root: TreeNode | None) -> None:
+ """
+ Display the flattened linked list.
+
+ Args:
+ root (TreeNode | None): The root of the flattened linked list.
+
+ Examples:
+ >>> root = TreeNode(1)
+ >>> root.right = TreeNode(2)
+ >>> root.right.right = TreeNode(3)
+ >>> display_linked_list(root)
+ 1 2 3
+ >>> root = None
+ >>> display_linked_list(root)
+
+ """
+ current = root
+ while current:
+ if current.right is None:
+ print(current.data, end="")
+ break
+ print(current.data, end=" ")
+ current = current.right
+
+
+if __name__ == "__main__":
+ print("Flattened Linked List:")
+ root = build_tree()
+ flatten(root)
+ display_linked_list(root)