Mercari coding interview
questions, leaked.
5 problems reported across recent Mercari interviews. Top patterns: array, math, greedy. The list below is what most reported candidates actually saw, plus the honest play if you can't grind all of it.
Mercari's assessment is deceptively light on the surface. Five problems total, mostly easy to medium, but they pack array, math, and greedy patterns into a tight rotation. You'll see the same three topics show up repeatedly across different problems, so you can't just memorize one solution per concept. The interview is designed to let you pass if you're sharp on fundamentals, but it punishes hesitation. If you hit a wall on a math or greedy problem mid-OA, StealthCoder surfaces a working approach in seconds, invisible to the proctor.
Top problems at Mercari
| # | Problem | Diff | Frequency | Pass % | Patterns |
|---|---|---|---|---|---|
| 01 | Smallest Missing Non-negative Integer After Operations | MEDIUM | 100.0 | 40% | Array · Hash Table · Math |
| 02 | Crawler Log Folder | EASY | 94.5 | 72% | Array · String · Stack |
| 03 | Max Difference You Can Get From Changing an Integer | MEDIUM | 94.5 | 49% | Math · Greedy |
| 04 | Count Largest Group | EASY | 94.5 | 75% | Hash Table · Math |
| 05 | Minimum Subsequence in Non-Increasing Order | EASY | 94.5 | 73% | Array · Greedy · Sorting |
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 Mercari OA. The proctor cannot see it. Screen share cannot detect it. Made for the engineer who has done the work but might still blank with a webcam pointed at him.
Get StealthCoderArray, math, and greedy each appear three times in the data. That's your signal: the assessment isn't testing breadth, it's testing whether you can code the same pattern under pressure in multiple contexts. Hash table comes up twice, usually paired with math or array problems. String, stack, and sorting appear once each, so they're edge cases, not centerpieces. The two medium problems both combine math with greedy or hash table, which means you can't just brute force; you need to see the optimization angle fast. Easy problems stick closer to straightforward simulation or counting. Drill array iteration, greedy selection logic, and hash-table lookups first. When you're confident on those, spend a session on the math problems that pair with greedy, because that's where candidates often blank. StealthCoder is your hedge if a greedy insight doesn't click in the first two minutes.
Companies with similar patterns
If you prepped for Mercari, these companies recycle ~60% of the same topics.
You've seen the list.
Now make sure you pass Mercari.
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 for the engineer who has done the work but might still blank with a webcam pointed at him. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Mercari interview FAQ
How many array problems should I solve to feel ready for Mercari?+
Array shows up in three of five problems. Solve at least five to ten array-focused drills covering iteration, in-place modification, and combining array logic with hash tables or greedy. Mercari's array problems often mix in another pattern, so practice hybrid approaches, not just pure array work.
Is Mercari harder or easier than other company assessments?+
Mercari's data is 60% easy, 40% medium, zero hard. Difficulty is low relative to other assessments, but don't underestimate the pacing. Problems layer multiple topics (array plus greedy, math plus hash table), so simplicity is deceptive. Speed matters more than raw difficulty.
What should I study first for this assessment?+
Start with greedy and array patterns in tandem. Three of the five problems involve greedy logic, and two of those also pull in array or hash table. Spend two to three sessions on greedy decision-making before moving to the math problems that pair with it.
Do I need to practice hash table problems extensively?+
Hash table appears twice in the five problems. It's not the centerpiece, but both times it pairs with math or array. Spend one focused session on hash-table counting and lookup patterns, then move on. Don't over-prepare on hash table at Mercari's expense.
How important is the math topic for Mercari?+
Math appears in three problems and both medium ones involve math plus greedy. You can't skip it. Focus on math problems that require optimization, not just calculation. Practice spotting the greedy or hash-table angle within math problems, because that's where the real work is.