Questions
8 of 26
1What is a Tree? Define Node, Root, Leaf, Edge, Height, Depth.
2What is a Binary Tree?
3What is a Binary Search Tree (BST)? What are its properties?
4What is the difference between a Binary Tree and a Binary Search Tree?
5Explain Tree Traversals: Inorder, Preorder, Postorder, Level Order.
6How do you implement Inorder traversal iteratively? (Without recursion)
7How do you find the Lowest Common Ancestor (LCA) of two nodes in a BST?
8How do you validate if a given Tree is a valid BST?
9What is a Balanced Tree? Why do we need balance?
10What is a Complete Binary Tree? A Full Binary Tree? A Perfect Binary Tree?
11What is a Heap? (Min-Heap and Max-Heap)
12How is a Heap implemented using an Array? (Parent/Child index math)
13What is the time complexity of insertion and deletion in a Heap? Why?
14What is Heapify? Explain the process.
15What is a Trie (Prefix Tree)? When is it used?
16How does a Trie compare to a Hash Table for string storage?
17What is an AVL Tree? What is a Red-Black Tree? What is the difference?
18Why do databases prefer B-Trees/B+ Trees over Binary Search Trees?
19How do you serialize and deserialize a Binary Tree?
20What is a Segment Tree? What problems does it solve?
21What is a Fenwick Tree (Binary Indexed Tree)?
22What is the difference between a B-Tree and a B+ Tree? Why are B+ Trees better for disk access?
23Explain the concept of Tree Rotation.
24What is a Splay Tree? When would you use it?
25How do you find the diameter of a Binary Tree?
26How do you check if a tree is symmetric (Mirror image)?
Data-StructuresData-Structures
Basics
Complexity Analysis
Arrays and Strings
Linked Lists
Stacks and Queues
Hash Tables
Trees
Graphs
08 / 26

How do you validate if a given Tree is a valid BST?

Difficulty: 3/10

BST Validation

javascript
  1. 1

    Carry lower and upper bounds to every subtree.

  2. 2

    Left subtree updates the upper bound.

  3. 3

    Right subtree updates the lower bound.

  4. 4

    Time complexity: O(n).

  5. 5

    Space complexity: O(h) due to recursion.

  6. 6

    The duplicate policy must be explicitly defined.

Follow-up Questions

  • Why is checking only parent-child relationships incorrect?
  • How can BST validation be implemented iteratively?
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