Overview
Binary tree ke nodes visit karna — inorder (left-root-right), preorder (root-left-right), postorder (left-right-root).
Analogy
Jaise family tree visit karna — inorder: junior se senior, preorder: boss pehle, postorder: children pehle.
Step-by-step
- Inorder: left -> root -> right (BST mein sorted order!)
- Preorder: root -> left -> right (tree copy/serialize)
- Postorder: left -> right -> root (tree delete, expression eval)
- Level order: BFS se
Visual
1
/ \
2 3
/ \
4 5
Inorder: 4,2,5,1,3
Preorder: 1,2,4,5,3
Postorder: 4,5,2,3,1
Common mistakes
- Inorder/preorder/postorder ka order yaad karna
- Null/None nodes handle karna
- Iterative vs recursive approach
Practice questions
- Teenon traversals recursive se implement karo
- Inorder traversal iterative stack se karo