Binary Search Tree Traversal Orders Explained
Binary Search Tree (BST) traversal defines the order nodes are visited, producing different output sequences critical for algorithms and coding interviews. Mastering inorder, preorder, and postorder traversal is essential for CS fundamentals courses, LeetCode problems, and technical interviews. Each traversal type is covered with clear definitions and recursive patterns.
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5 CardsWhat is level-order traversal?
BST inorder output for: 4, 2, 6, 1, 3
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What is the difference between inorder and preorder BST traversal?
Inorder (left → root → right) visits the root between its children, producing sorted output for BSTs. Preorder (root → left → right) visits the root first, useful for copying or serializing trees.
- Inorder: sorted output
- Preorder: root-first, tree duplication
Why does inorder traversal produce sorted output in a BST?
A BST enforces that all left descendants are smaller and all right descendants are larger than the root. Inorder traversal visits left before root before right, naturally producing ascending sorted order.
How do I remember the three BST traversal orders?
Use the position of root relative to subtrees:
- Preorder = root before children
- Inorder = root in between children
- Postorder = root after children