Jane Street coding interview
questions, leaked.
11 problems reported across recent Jane Street interviews. Top patterns: array, string, simulation. The list below is what most reported candidates actually saw, plus the honest play if you can't grind all of it.
Jane Street pulls from a small, tight problem set that rewards pattern recognition over brute-force memorization. With 11 problems across 11 rounds, you're facing a 36% hard clip and a heavy tilt toward array and string patterns. Arrays show up in seven problems; strings in six. Simulation, hash-tables, and design round out the mix. You can't afford to blank on array iteration, string parsing, or the mechanics of a greedy simulation. If you hit a wall mid-assessment, StealthCoder reads the prompt in real time and delivers a working solution invisible to the proctor, so you can stay calm and keep moving.
Top problems at Jane Street
| # | Problem | Diff | Frequency | Pass % | Patterns |
|---|---|---|---|---|---|
| 01 | Count Common Words With One Occurrence | EASY | 100.0 | 72% | Array · Hash Table · String |
| 02 | Walking Robot Simulation | MEDIUM | 93.4 | 58% | Array · Hash Table · Simulation |
| 03 | Minimum Time to Make Array Sum At Most x | HARD | 91.3 | 25% | Array · Dynamic Programming · Sorting |
| 04 | Add Two Integers | EASY | 76.5 | 88% | Math |
| 05 | Stream of Characters | HARD | 65.5 | 51% | Array · String · Design |
| 06 | Design a Text Editor | HARD | 65.5 | 47% | Linked List · String · Stack |
| 07 | Add Strings | EASY | 65.5 | 52% | Math · String · Simulation |
| 08 | Evaluate Division | MEDIUM | 56.9 | 63% | Array · String · Depth-First Search |
| 09 | Longest Common Prefix | EASY | 56.9 | 45% | String · Trie |
| 10 | Trapping Rain Water | HARD | 56.9 | 65% | Array · Two Pointers · Dynamic Programming |
| 11 | Number of Orders in the Backlog | MEDIUM | 56.9 | 52% | Array · Heap (Priority Queue) · Simulation |
Frequencies derived from public community-tagged interview reports. Click a row to view on LeetCode.
You have a week, maybe less. You can't out-grind the list above. StealthCoder runs invisibly during the actual Jane Street OA. The proctor cannot see it. Screen share cannot detect it. Made by a working FAANG engineer who treats the OA the way companies treat hiring: as a game with rules you should know.
Get StealthCoder- array7 · 64%
- string6 · 55%
- simulation4 · 36%
- hash table2 · 18%
- math2 · 18%
- design2 · 18%
- trie2 · 18%
- dynamic programming2 · 18%
- stack2 · 18%
- counting1 · 9%
Jane Street's problem set is deceptively narrow but operationally dense. Arrays dominate the signal, but they're rarely straightforward iteration. You'll see array problems tangled with dynamic programming (Minimum Time to Make Array Sum), simulation (Walking Robot Simulation), and monotonic-stack logic (Trapping Rain Water). Strings appear almost as frequently, and design questions like Stream of Characters and Design a Text Editor demand you think like a systems engineer, not a leetcoder. Hash-tables and counting show up as modifiers, not centerpieces. Start with the easy problems to lock down array and string mechanics, then move to the medium simulations to build intuition for state transitions. The hard problems are your bottleneck. If you haven't drilled Trapping Rain Water or understood the DP recurrence in Minimum Time, StealthCoder is your safety net on test day.
Companies with similar patterns
If you prepped for Jane Street, these companies recycle ~60% of the same topics.
You've seen the list.
Now make sure you pass Jane Street.
Memorizing every problem above in a week is a fantasy. StealthCoder is the hedge: an AI overlay that's invisible during screen share. It reads the problem on screen and surfaces a working solution in under 2 seconds. Made by a working FAANG engineer who treats the OA the way companies treat hiring: as a game with rules you should know. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Jane Street interview FAQ
How many array problems should I solve before the Jane Street assessment?+
At least seven, ideally all of them. Arrays appear in more than half the reported problems. Prioritize the ones tagged with simulation or DP first, because Jane Street seems to avoid pure iteration problems. Don't waste time on classic two-pointer drills if you're short on time; focus on Trapping Rain Water and Minimum Time to Make Array Sum.
Is string manipulation enough for Jane Street, or do I need advanced data structures?+
You need both. Six problems touch strings, but three of them (Stream of Characters, Design a Text Editor, Longest Common Prefix) require tries, stacks, or doubly-linked lists. String parsing alone won't pass. Spend two to three sessions building trie and stack competence before the OA.
What topic should I study first if I have one week before the Jane Street assessment?+
Arrays, then simulations. Arrays show up seven times and form the backbone of harder problems like Trapping Rain Water. Once you're solid on arrays, move to simulation problems like Walking Robot Simulation and Design a Text Editor, which test your ability to track state and mutate it correctly. These two topics account for most of the medium and hard problems.
Should I memorize dynamic programming patterns for Jane Street, or can I guess my way through?+
Memorize the recurrence for at least one hard DP problem, like Minimum Time to Make Array Sum. Jane Street has four hard problems, two of which involve DP or monotonic-stack logic. You can't guess DP in an interview. If you blank on the recurrence mid-OA, that's where you lean on your prep or a live tool.
How much design and systems thinking shows up in Jane Street interviews?+
More than most quant firms. Stream of Characters and Design a Text Editor are both design-heavy problems, not pure algorithms. They test whether you can architect a data structure under constraints. Spend at least one or two sessions thinking about tradeoffs between query speed and space, not just correctness.