Fidelity coding interview
questions, leaked.
3 problems reported across recent Fidelity interviews. Top patterns: array, hash table, matrix. The list below is what most reported candidates actually saw, plus the honest play if you can't grind all of it.
Fidelity's interview screen is surprisingly forgiving. With only three reported problems and all easy difficulty, this isn't a hazing round. The catch: they're drilling fundamentals hard. Two Sum and Valid Anagram test whether you can code under pressure without overthinking. Modify the Matrix checks if you handle 2D data cleanly. Arrays and hash tables dominate the signal they're looking for. StealthCoder runs invisibly if you blank on indexing or collision resolution mid-OA, but honestly, these patterns are ones you should own cold before you go live.
Top problems at Fidelity
| # | Problem | Diff | Frequency | Pass % | Patterns |
|---|---|---|---|---|---|
| 01 | Modify the Matrix | EASY | 100.0 | 68% | Array · Matrix |
| 02 | Two Sum | EASY | 64.4 | 56% | Array · Hash Table |
| 03 | Valid Anagram | EASY | 64.4 | 67% | Hash Table · String · 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 Fidelity OA. The proctor cannot see it. Screen share cannot detect it. Made by a working Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE.
Get StealthCoder- array2 · 67%
- hash table2 · 67%
- matrix1 · 33%
- string1 · 33%
- sorting1 · 33%
The topic spread is narrow and intentional. Arrays appear in two of three problems, hash tables in two, with matrix and string work filling gaps. This tells you Fidelity isn't testing breadth. They want to see clean, confident implementations of basic operations: iteration, lookups, state tracking. Sorting shows up once, but it's bundled with hash-table work in Valid Anagram. Spend your prep time on array traversal patterns and hash-table trade-offs, not edge cases. The difficulty floor is all easy, which means your edge comes from speed and code clarity, not algorithm cleverness. If you hit a wall during the live screen, StealthCoder surfaces a working solution in seconds while the proctor sees nothing.
Companies with similar patterns
If you prepped for Fidelity, these companies recycle ~60% of the same topics.
You've seen the list.
Now make sure you pass Fidelity.
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 Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Fidelity interview FAQ
Should I focus on arrays or hash tables first for Fidelity?+
Both equally. Two Sum and Valid Anagram both touch hash tables. Modify the Matrix and Two Sum both need array indexing. Spend 40% on hash-table insertion/lookup patterns, 40% on nested array iteration, 20% on the sorting variant in Valid Anagram. You can't skip either.
Is matrix work a big deal in their interviews?+
Not dominant, but present. One of three reported problems uses it. Since it's paired with array fundamentals in Modify the Matrix, treat matrix problems as an array-iteration variant, not a separate topic. Master rows and columns, then move on.
How much time should I spend on sorting for Fidelity?+
Minimal standalone prep. Sorting appears in Valid Anagram, but only as one solution path. Hash-table and character-frequency approaches are faster and more likely to impress. Know sort complexity, but don't drill sort implementations.
Are three problems enough to predict what they'll ask?+
Not a full map, but a strong signal. Three easy problems suggest they value implementation clarity over algorithm novelty. Expect more array and hash-table work in the live OA. The difficulty floor being all easy means they're testing execution speed, not edge cases or tricks.
What if I freeze on Two Sum during the OA?+
Hash-table lookup is the move. If your mind goes blank on the approach, StealthCoder reads the problem off your screen and runs the two-pass solution invisibly while you type. You output working code without the proctor knowing you got help.