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Suggest the next problem in a series after a pass

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#536 1 comment 0 reactions 1 assignee View on GitHub

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@peter1001136 is already working on this.

Since Oct 28, 2026.

  • #537 by @peter1001136 — merged

Assessment

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Description

Who is affected

Candidates practising one technique at a time. A candidate who draws Chargeback Pair Match (LeetCode 1, Easy) and finishes it would often like the same idea with one more constraint next, Gift Card Bundle Pair (LeetCode 167, Medium); after Billboard Pole Banner (LeetCode 11, Medium), that is Terrain Runoff Pooling (LeetCode 42, Hard). The bank holds both halves of each pair, but nothing connects them.

Current behavior

Back in the lobby, nothing refers to the problem just finished. The selected problem comes from pickProblem (web/problem-picker.js:154): a due review, else a random problem not yet passed at the checked levels, else any. The bank has no field relating one problem to another (problem-bank/problems.json holds constraints, difficulty, examples, id, optimal, pitfalls, starterCode, statement, summary, title and topics), so the candidate has to know the LeetCode series and look for its next problem by hand.

Desired outcome

When the candidate's latest interview passed a problem that has a sequel they have not passed, the lobby shows one suggestion beside the selected problem, for example "You passed Chargeback Pair Match. Next in this series: Gift Card Bundle Pair (Medium)", with a button that selects it. The suggestion changes nothing until it is pressed: the selected problem, "Pick a random problem", due reviews and the practice list all behave as they do today. A sequel is exactly one level harder, so an Easy problem suggests a Medium one and a Medium problem a Hard one, whatever levels are checked. Each interview stays one problem, so the interview contract, the report schema and the history format are untouched.

Proposed scope

A sequel uses the same technique one level up. The pairs the bank already holds:

Passed Suggested sequel
best-time-to-buy-and-sell-stock (Single Resale Window, Easy) best-time-to-buy-and-sell-stock-ii (Single Slot Reseller, Medium)
remove-duplicates-from-sorted-array (Telemetry Reading Dedupe, Easy) remove-duplicates-from-sorted-array-ii (Alert Digest Trimming, Medium)
single-number (Unmatched Badge Scan, Easy) single-number-ii (Replica Write Audit, Medium)
two-sum (Chargeback Pair Match, Easy) two-sum-ii-input-array-is-sorted (Gift Card Bundle Pair, Medium)
search-insert-position (Sorted Schedule Slot, Easy) find-first-and-last-position-of-element-in-sorted-array (Log Timestamp Span, Medium)
valid-parentheses (Template Delimiter Audit, Easy) generate-parentheses (Nesting Fuzzer Corpus, Medium)
climbing-stairs (Robot Stride Plans, Easy) house-robber (Highway Billboard Leasing, Medium)
best-time-to-buy-and-sell-stock-ii (Single Slot Reseller, Medium) best-time-to-buy-and-sell-stock-iii (Spot Capacity Round Trips, Hard)
word-search (Letter Panel Tracing, Medium) word-search-ii (Letter Grid Tracer, Hard)
container-with-most-water (Billboard Pole Banner, Medium) trapping-rain-water (Terrain Runoff Pooling, Hard)
minimum-genetic-mutation (Approved Sequence Edits, Medium) word-ladder (Hostname Rename Chain, Hard)
longest-substring-without-repeating-characters (Distinct Keystroke Stretch, Medium) minimum-window-substring (Required Marker Span, Hard)
reverse-linked-list-ii (Playlist Segment Flip, Medium) reverse-nodes-in-k-group (Radio Frame Batching, Hard)
evaluate-reverse-polish-notation (Pricing Rule Bytecode, Medium) basic-calculator (Budget Sheet Formulas, Hard)
kth-largest-element-in-an-array (Rating Leaderboard Cutoff, Medium) find-median-from-data-stream (Live Clock Offset Monitor, Hard)
permutations (Startup Order Sweep, Medium) n-queens-ii (Interference Free Towers, Hard)
sort-list (Firmware Event Chain Ordering, Medium) merge-k-sorted-lists (Shard Result Consolidation, Hard)
find-first-and-last-position-of-element-in-sorted-array (Log Timestamp Span, Medium) median-of-two-sorted-arrays (Twin Sensor Midpoint Reading, Hard)
  1. A sequel field in problem-bank/problems.json, on the problem that leads to it. The generator refuses a sequel that is not a problem in the bank or is not exactly one level harder than the problem naming it, so the table above is the whole rule and a reviewer can change a pair by editing one line.
  2. scripts/gen-problem-cards.py writes it onto the card as data-sequel, beside data-difficulty (:59), and web/app.js reads it into cards (:200).
  3. A pure function beside pickProblem reads the history the lobby already loads and returns the suggestion, or none; the lobby renders it next to the selected problem, and its button selects the sequel the way choosing its card does. pickProblem itself is unchanged.
Acceptance criteria
  • After a pass on a problem with a sequel the candidate has not passed, the lobby shows the suggestion, including when the sequel's level is not checked, and pressing it selects the sequel.
  • After a fail, an unscored interview, a pass on a problem without a sequel, or a pass whose sequel is already passed, no suggestion is shown.
  • Until the suggestion is pressed, the selected problem, the random draw, due reviews and the practice-list draw are unchanged.
  • tests/browser/problem-picker.test.js covers each case of the function, a lobby test covers showing and pressing the suggestion, and the generator check fails on a sequel that is missing, not harder, or two levels harder.
Decision needed

Should the suggestion follow only a pass, as above, or any finished interview on the problem? I would keep it to a pass: a candidate who failed the Easy problem is better served by the review it is already scheduled for than by a harder one.

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