Part 1 · 1 chapters · ~8 min
Coding Rounds
The structure of a 45-minute round, clarifying and examples, brute force then optimise, the 15 patterns that cover most questions (from the DSA course), narrating while coding, testing by hand, handling being stuck, practical rounds (build a feature, debug a codebase, review a PR), and practising with a timer.
2
Patterns and practice
| pattern | signal in the question | Learna |
|---|---|---|
| hash map counting / lookup | "find pairs", "duplicates", "first unique" | DSA P3 (includes vs Set.has: 200.6 vs 1.1 ms measured) |
| two pointers / sliding window | sorted input, contiguous subarray, "at most k" | DSA P11 |
| binary search (on answers too) | sorted, monotonic condition, "minimum capacity" | DSA P11 |
| BFS / DFS / topological sort | grids, dependencies, shortest steps | DSA P6, Discrete P5 |
| heap / top-k | "k largest", "merge k sorted", scheduling | DSA P5 |
| dynamic programming | "number of ways", "minimum cost", overlapping subproblems | DSA P7, Discrete P8 |
| intervals | meetings, merging ranges, overlaps | DSA P11 |
Practical rounds are increasingly common at senior levels: extend an existing codebase, debug a failing service, or review a pull request. Practise reading unfamiliar code quickly (Merge Reviews course) and using the debugger and logs (Backend Diagnosis). When stuck: say what you are trying, simplify the problem (smaller input, sorted input), and ask a targeted question.
A CODING ROUND, MINUTE BY MINUTE
45 minutes, scored on how as much as what
swipe the figure sideways, or tap expand for full screen
1/4
clarify
Restate the problem, ask about input sizes and edge cases (empty, duplicates, negative amounts), and write one example. Many failures come from solving the wrong problem.
restate, ask, examplesolve the right problem