Height and Depth:
- Binary Tree
- Binary Search Tree
- AVL Tree
- B-Tree
- Red Black Tree
Patterns of questions: (leetcode list)
2. Root to leaf path problems
3. Serialize and deserialize
4. Leaves related problem
5. Level order traversal
6. Node deletion
7. Tree construction
8. Distance between two Nodes
9. Inorder traversal
10. Flipping
11. Check binary tree
12. Tree relations
13. Counting of nodes
14. Recovery
15. Kth smallest
16. Trimming or pruning
17. Searching
18. Difference problem in BT
19. Tree checking
20. Depth problems