A Binary Search Tree (BST) is a type of binary tree data structure in which each node contains a unique key and satisfies a specific ordering property:
- All nodes in the left subtree of a node contain values strictly less than the node’s value.
- All nodes in the right subtree of a node contain values strictly greater than the node’s value.
This structure enables efficient operations for searching, insertion, and deletion of elements, especially when the tree remains balanced.
Key Properties
- Unique ordering of elements means duplicates are usually not allowed.
- Inorder traversal of a BST gives sorted order of elements.
- Average height: O(log n) (for balanced BST).
- Worst case height: O(n) (when tree is skewed or forms a line).
Basics
- Applications
- Insertion, Search and Delete
- Minimum and Maximum
- Floor and Ceil
- Inorder Successor and Inorder Predecessor
Easy Problems
- Second Largest
- Sum of k Smallest
- BST Keys in Range
- BST to Balanced BST
- Check for BST
- Binary Tree to BST
- Check if array is Inorder of BST
- Sorted Array to Balanced BST
- Check Equal BSTs
- BST to Min Heap
- Add all greater values in a BST
- Check if two BSTs have same elements
Medium Problems
- BST from Preorder
- Sorted Linked List to Balanced BST
- Transform a BST to greater sum tree
- BST to a Tree with sum of all smaller keys
- Construct BST from Level Order
- Check for Level Order of BST
- Max Sum with No Two Adjacent in BST
- LCA in a BST
- Distance between Two Nodes
- k-th Smallest in BST
- Largest BST in a Binary Tree | Set 2
- Remove all leaves from BST
- 2 sum in BST
- Max between two nodes of BST
- Largest BST Subtree
- 2 Sum in a Balanced BST
- Fix a BST with 2 swapped
- Leaf nodes from Preorder of a BST
- Check if an Array can represent BST
Hard Problems
- All possible BSTs for keys 1 to N
- In-place Convert BST into a Min-Heap
- Merge two BSTs
- K’th Largest in BST without change
- Check for Subsequence
- Max Subarray Unique Element
- Pairs with sum from two BSTs
- 3 Sum in a Balanced BST
- Replace with the least greater on right
- Leaf nodes from Preorder
- Minimum Possible value of |ai + aj – k|
- Special two digit numbers in a BST
Important Links
