Tree Data Structure Questions for Data Structures and Algorithms.

1. Tree Basics and Traversals

• Implement a Binary Tree.
• Preorder Traversal (Recursive and Iterative).
• Inorder Traversal (Recursive and Iterative).
• Postorder Traversal (Recursive and Iterative).
• Level Order Traversal (BFS).
• Reverse Level Order Traversal.
• Spiral/Zigzag Level Order Traversal.
• Boundary Traversal of a Binary Tree.
• Diagonal Traversal of a Binary Tree.
• Vertical Order Traversal of a Binary Tree.
• Find the Lowest Common Ancestor (LCA) in a Binary Tree.

2. Binary Tree Construction Problems

• Construct a Binary Tree from Inorder and Preorder Traversal.
• Construct a Binary Tree from Inorder and Postorder Traversal.
• Construct a Binary Tree from Level Order and Inorder Traversal.
• Construct a Special Tree from Inorder Traversal (Tree with Only One Child Nodes).
• Construct a Full Binary Tree from Preorder and Postorder Traversal.
• Construct a Binary Tree from its Mirror Image.
• Convert a Binary Tree to its Mirror Tree.
• Convert a Binary Tree to a Doubly Linked List.
• Construct a Threaded Binary Tree.
• Build a Tree from Inorder and Level Order Traversal.
• Construct a Binary Tree from Postorder and Level Order Traversal.

3. Tree Properties and Analysis

• Find the Height of a Binary Tree.
• Find the Depth of a Given Node.
• Check if a Tree is Symmetric.
• Check if Two Trees are Identical.
• Diameter of a Binary Tree.
• Check if a Binary Tree is Balanced (Height Balanced).
• Check if a Binary Tree is a Sum Tree.
• Maximum Path Sum in a Binary Tree.
• Check if a Binary Tree is Perfect.
• Check if a Binary Tree is Complete.
• Find the Kth Smallest and Kth Largest Element in a Binary Search Tree (BST).

4. Tree Modification and Manipulation

• Convert a Binary Tree to a Sum Tree.
• Convert a Binary Tree to a Child-Sum Property Tree.
• Convert a Binary Tree to a Doubly Linked List.
• Convert a Binary Tree into a Circular Doubly Linked List.
• Convert a Binary Tree to a Threaded Binary Tree.
• Flatten a Binary Tree to a Linked List.
• Convert a Binary Tree to a List of Levels.
• Convert a Binary Tree to an Inverted Tree.
• Add All Greater Values to Every Node in a Binary Search Tree (BST).
• Merge Two Binary Trees.
• Convert a Binary Tree to a Skewed Binary Tree.

5. Binary Search Tree (BST) Problems

• Insert a Node in a BST.
• Delete a Node in a BST.
• Search for a Node in a BST.
• Find the Minimum and Maximum Value in a BST.
• Find the Inorder Successor and Predecessor in a BST.
• Check if a Given Tree is a BST.
• Convert a BST to a Greater Sum Tree.
• Lowest Common Ancestor (LCA) in a BST.
• Check if a BST is Height Balanced.
• Merge Two BSTs into a Balanced BST.
• Find the Maximum Sum Path in a BST.

6. Tree Views

• Left View of a Binary Tree.
• Right View of a Binary Tree.
• Top View of a Binary Tree.
• Bottom View of a Binary Tree.
• Print All Leaf Nodes from Left to Right.
• Print All Leaf Nodes from Right to Left.
• Boundary View of a Binary Tree.
• Print the Longest Path in a Binary Tree.
• Print Nodes at Distance K from the Root.
• Print Nodes at Distance K from a Given Node.
• Find All Nodes at Distance K from the Leaf Nodes.

7. Tree Recursive Problems

• Print All Ancestors of a Given Node.
• Print All Paths from Root to Leaf.
• Print the Path from Root to a Given Node.
• Find the Kth Smallest Element in a BST.
• Find the Kth Largest Element in a BST.
• Find the Lowest Common Ancestor (LCA) in a Binary Tree.
• Count Leaf Nodes in a Binary Tree.
• Count Non-Leaf Nodes in a Binary Tree.
• Count Nodes with Exactly One Child in a Binary Tree.
• Count Nodes with Two Children in a Binary Tree.
• Find the Depth of a Given Node in a Binary Tree.

8. Tree Algorithms and Techniques

• Morris Traversal (Inorder and Preorder without Recursion and Stack).
• Threaded Binary Tree Traversal.
• Finding the Maximum Width of a Binary Tree.
• Serialize and Deserialize a Binary Tree.
• Check if a Binary Tree is a Subtree of Another Tree.
• Find the Largest BST in a Binary Tree.
• Find All Nodes at Distance K in a Binary Tree.
• Convert a Binary Tree to a Circular Doubly Linked List.
• Inorder Successor in a BST without Using Parent Pointer.
• Flatten a Binary Tree into a List of Levels.
• Implement Level Order Traversal using Iteration.

9. Tree-Based Dynamic Programming

• Maximum Path Sum in a Binary Tree.
• Maximum Sum of Nodes without Adjacent Nodes.
• Diameter of a Binary Tree using DP.
• Largest Independent Set Problem in a Binary Tree.
• House Robber Problem (Binary Tree Version).
• Longest Path Between Any Two Nodes.
• Count Number of Subtrees with a Given Sum.
• Find the Longest Consecutive Sequence Path in a Binary Tree.
• Check if a Tree can be Partitioned into Two Trees with Equal Sum.
• Count Number of Unique BSTs (Catalan Number).
• Find All Unique Paths from Root to Leaf.

10. Tree Miscellaneous Problems

• Check if a Tree is a Mirror of Itself (Symmetric).
• Convert Sorted Array to a Balanced BST.
• Convert Sorted Linked List to a Balanced BST.
• Print Nodes in the Topological Order of a Binary Tree.
• Sum of All Nodes in a Binary Tree.
• Sum of All Left Leaves in a Binary Tree.
• Sum of All Right Leaves in a Binary Tree.
• Print the Vertical Sum of a Binary Tree.
• Find All Duplicate Subtrees in a Binary Tree.
• Find the Maximum Sum Subtree in a Binary Tree.
• Count the Number of Nodes in a Complete Binary Tree.

These questions encompass a range of fundamental and advanced topics related to trees in data structures and algorithms, making them essential for mastering this important area of computer science.

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