DSA Pattern Guide
Trees & BSTs Interview Patterns
Tree interview problems are almost always a traversal (DFS pre/in/post-order or BFS level-order) combined with what you track along the way — a running sum, a depth, a pair of ancestors. BST problems add one fact: in-order traversal of a BST visits nodes in sorted order, which is the key insight behind most BST-specific questions.
5
Problems in Ediky's DSA bank
17
Questions in Ediky's DSA-Technical bank
5 problems is thin for a topic this central to interviews — being upfront about that rather than overselling it. The DSA-Technical bank's 17 questions are the deeper resource for now. Ediky also doesn't split out a separate "BST" tag from general "Tree" yet, so BST-specific problems aren't independently filterable.
The patterns that matter
- DFS traversal (pre/in/post-order) — the default tool for most tree problems
- BFS / level-order traversal — when the answer depends on depth or level
- In-order traversal on a BST — visits nodes in sorted order; the basis for most BST-specific questions
- Tracking state through recursion — running sums, ancestor chains, subtree properties
Real problems from Ediky
From the DSA bank (code-judged):
- "Disk Storage" (Tree)
- "Building Monuments" (Tree)
- "Longest Compatible Transmission Path" (Tree)
Practice Tree problems
5 code-judged Tree problems, plus 17 deeper trace/MCQ questions in DSA-Technical.
Open Tree problems