Roche coding interview
questions, leaked.
2 problems reported across recent Roche interviews. Top patterns: string, trie, math. The list below is what most reported candidates actually saw, plus the honest play if you can't grind all of it.
Roche's coding assessment is small and focused. Two reported problems, both easy, both core patterns you've probably seen before. One is a classic string/trie problem (Longest Common Prefix), the other is pure math (Palindrome Number). The interview is rigged in your favor here: the bar is low, the patterns are textbook, and you have time to own them before you sit down. If you blank on either during the live assessment, StealthCoder runs invisibly and surfaces a working solution in seconds.
Top problems at Roche
| # | Problem | Diff | Frequency | Pass % | Patterns |
|---|---|---|---|---|---|
| 01 | Longest Common Prefix | EASY | 100.0 | 45% | String · Trie |
| 02 | Palindrome Number | EASY | 100.0 | 59% | Math |
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 Roche OA. The proctor cannot see it. Screen share cannot detect it. Built by an engineer at a top-10 tech company who can solve these problems cold but didn't want to trust himself in a 90-minute screen share.
Get StealthCoderThe topic distribution is tight: string and trie problems account for half the data, with math rounding it out. This isn't a deep technical assessment. It's a filter for whether you can code basic algorithms without panicking. String manipulation and number theory are your focus. Both problems are easy, which means time pressure is low but precision matters. Palindrome Number in particular tests whether you can handle integer reversal and edge cases cleanly. If you practice both patterns to muscle memory, you'll walk in confident. StealthCoder is your hedge if you second-guess yourself on the live OA.
Companies with similar patterns
If you prepped for Roche, these companies recycle ~60% of the same topics.
You've seen the list.
Now make sure you pass Roche.
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. Built by an engineer at a top-10 tech company who can solve these problems cold but didn't want to trust himself in a 90-minute screen share. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Roche interview FAQ
How many string and trie problems should I drill before the Roche assessment?+
Drill Longest Common Prefix until you can code it three ways in under five minutes each: recursive, iterative, and horizontal scanning. That single problem represents 50% of the reported topics. Master it cold and you've covered the hard half.
Is math really 50% of the Roche interview?+
Based on reported data, yes. Palindrome Number is one of two problems. It's pure math, no data structures. Spend time on integer reversal, mod/division logic, and edge cases like negative numbers. Don't overthink it.
Are both problems actually easy, or is the difficulty misreported?+
Both are confirmed easy. No medium or hard problems reported. The bar is basic algorithm fluency. The risk isn't algorithmic complexity. It's rushing, typos, and off-by-one errors. Code slow and test your edge cases.
What's the fastest way to prep for two easy problems?+
Code Longest Common Prefix five times. Code Palindrome Number five times. Test edge cases each time. Spend two hours max. Both are reference implementations in any DSA book. Don't over-prepare for a low bar.
Should I study hard problems for Roche if only easy ones are reported?+
No. The data shows zero hard problems. If a curveball appears during the assessment, you're not going to have time to solve it anyway. Master easy first. Stay confident. Let StealthCoder catch anything unexpected.