Binary Search Tree LeetCode Problems: All 40, With Python Solutions
Every problem in this library that LeetCode tags Binary Search Tree — 40 in total, 29 of them with a complete Python solution, a worked example and the time and space complexity of the approach.
- 40 problems
- 10 Easy
- 27 Medium
- 3 Hard
How Binary Search Tree problems are solved
A tag names the subject, not the method. These pattern hubs cover the techniques that actually solve Binary Search Tree problems — each one explains the approach, gives a Python template and states its complexity.
- Tree Traversal — Choose the order — preorder, inorder, postorder, level — and the problem solves itself.
Binary Search Tree problems by difficulty
Problems with a complete Python solution are listed first, then by ascending problem number.
Easy (10)
| # | Problem | Difficulty | Topics |
|---|---|---|---|
| 108 | Convert Sorted Array to Binary Search Tree | Easy | Tree, Binary Search Tree, Array +2 |
| 501 | Find Mode in Binary Search Tree | Easy | Tree, Depth-First Search, Binary Search Tree +1 |
| 530 | Minimum Absolute Difference in BST | Easy | Tree, Depth-First Search, Breadth-First Search +2 |
| 653 | Two Sum IV - Input is a BST | Easy | Tree, Depth-First Search, Breadth-First Search +4 |
| 700 | Search in a Binary Search Tree | Easy | Tree, Binary Search Tree, Binary Tree |
| 703 | Kth Largest Element in a Stream | Easy | Tree, Design, Binary Search Tree +3 |
| 783 | Minimum Distance Between BST Nodes | Easy | Tree, Depth-First Search, Breadth-First Search +2 |
| 897 | Increasing Order Search Tree | Easy | Stack, Tree, Depth-First Search +2 |
| 938 | Range Sum of BST | Easy | Tree, Depth-First Search, Binary Search Tree +1 |
| 270 | Closest Binary Search Tree ValuePremium | Easy | Tree, Depth-First Search, Binary Search Tree +2 |
Medium (27)
| # | Problem | Difficulty | Topics |
|---|---|---|---|
| 95 | Unique Binary Search Trees II | Medium | Tree, Binary Search Tree, Dynamic Programming +2 |
| 96 | Unique Binary Search Trees | Medium | Tree, Binary Search Tree, Math +2 |
| 98 | Validate Binary Search Tree | Medium | Tree, Depth-First Search, Binary Search Tree +1 |
| 99 | Recover Binary Search Tree | Medium | Tree, Depth-First Search, Binary Search Tree +1 |
| 109 | Convert Sorted List to Binary Search Tree | Medium | Tree, Binary Search Tree, Linked List +2 |
| 173 | Binary Search Tree Iterator | Medium | Stack, Tree, Design +3 |
| 230 | Kth Smallest Element in a BST | Medium | Tree, Depth-First Search, Binary Search Tree +1 |
| 235 | Lowest Common Ancestor of a Binary Search Tree | Medium | Tree, Depth-First Search, Binary Search Tree +1 |
| 449 | Serialize and Deserialize BST | Medium | Tree, Depth-First Search, Breadth-First Search +4 |
| 450 | Delete Node in a BST | Medium | Tree, Binary Search Tree, Binary Tree |
| 538 | Convert BST to Greater Tree | Medium | Tree, Depth-First Search, Binary Search Tree +1 |
| 669 | Trim a Binary Search Tree | Medium | Tree, Depth-First Search, Binary Search Tree +1 |
| 701 | Insert into a Binary Search Tree | Medium | Tree, Binary Search Tree, Binary Tree |
| 1008 | Construct Binary Search Tree from Preorder Traversal | Medium | Stack, Tree, Binary Search Tree +3 |
| 1038 | Binary Search Tree to Greater Sum Tree | Medium | Tree, Depth-First Search, Binary Search Tree +1 |
| 1305 | All Elements in Two Binary Search Trees | Medium | Tree, Depth-First Search, Binary Search Tree +2 |
| 1382 | Balance a Binary Search Tree | Medium | Greedy, Tree, Depth-First Search +3 |
| 2476 | Closest Nodes Queries in a Binary Search Tree | Medium | Tree, Depth-First Search, Binary Search Tree +3 |
| 255 | Verify Preorder Sequence in Binary Search TreePremium | Medium | Stack, Tree, Binary Search Tree +4 |
| 285 | Inorder Successor in BSTPremium | Medium | Tree, Depth-First Search, Binary Search Tree +1 |
| 333 | Largest BST SubtreePremium | Medium | Tree, Depth-First Search, Binary Search Tree +2 |
| 426 | Convert Binary Search Tree to Sorted Doubly Linked ListPremium | Medium | Stack, Tree, Depth-First Search +4 |
| 510 | Inorder Successor in BST IIPremium | Medium | Tree, Binary Search Tree, Binary Tree |
| 776 | Split BSTPremium | Medium | Tree, Binary Search Tree, Recursion +1 |
| 1214 | Two Sum BSTsPremium | Medium | Stack, Tree, Depth-First Search +4 |
| 1586 | Binary Search Tree Iterator IIPremium | Medium | Stack, Tree, Design +3 |
| 1902 | Depth of BST Given Insertion OrderPremium | Medium | Tree, Binary Search Tree, Array +2 |
Hard (3)
| # | Problem | Difficulty | Topics |
|---|---|---|---|
| 1373 | Maximum Sum BST in Binary Tree | Hard | Tree, Depth-First Search, Binary Search Tree +2 |
| 1569 | Number of Ways to Reorder Array to Get Same BST | Hard | Tree, Union Find, Binary Search Tree +7 |
| 272 | Closest Binary Search Tree Value IIPremium | Hard | Stack, Tree, Depth-First Search +4 |
Keep exploring
All LeetCode topicsEvery tag with a page of its own, with the number of problems behind each.LeetCode patternsThe techniques themselves, with a Python template and complexity for each.Curated study listsBlind 75, NeetCode 150 and three more, grouped by pattern.Easy problemsStart here when the data structure is new rather than the problem.
Other topics
- Array1,569
- String672
- Hash Table588
- Math485
- Dynamic Programming481
- Sorting392
- Greedy346
- Depth-First Search289
- Binary Search253
- Database249
- Tree225
- Breadth-First Search223
- Matrix216
- Two Pointers201
- Bit Manipulation194
- Binary Tree174
- Heap (Priority Queue)163
- Prefix Sum157
- Stack157
- Simulation144
- Graph138
- Counting126
- Design122
- Sliding Window116
When the Binary Search Tree problem arrives live
Stealth Interview is a desktop app for macOS and Windows. It reads the coding problem off your screen, returns a working solution with a step-by-step explanation and its time and space complexity, and transcribes what the interviewer is saying — while staying invisible to screen sharing.