Circle coding interview
questions, leaked.
2 problems reported across recent Circle interviews. Top patterns: hash table, design, string. The list below is what most reported candidates actually saw, plus the honest play if you can't grind all of it.
Circle's interview hits you with design problems right out of the gate. Two reported problems, and both are medium-to-hard system-design tasks that blend hash tables, strings, and data structure manipulation. You're not solving leetcode classics here. You're building a bank system or file system from scratch under time pressure. If you've prepped arrays and sorting in isolation, you're walking in cold. StealthCoder runs invisible during the assessment and surfaces working implementations the moment you hit a wall on either problem.
Top problems at Circle
| # | Problem | Diff | Frequency | Pass % | Patterns |
|---|---|---|---|---|---|
| 01 | Simple Bank System | MEDIUM | 100.0 | 61% | Array · Hash Table · Design |
| 02 | Design In-Memory File System | HARD | 90.6 | 48% | Hash Table · String · Design |
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 Circle OA. The proctor cannot see it. Screen share cannot detect it. Made by an Amazon engineer who watched the leaked-problem repo become an industry secret. He decided you should have it too.
Get StealthCoder- hash table2 · 100%
- design2 · 100%
- string1 · 50%
- trie1 · 50%
- sorting1 · 50%
- array1 · 50%
- simulation1 · 50%
Hash tables dominate Circle's reported problems, appearing in both top submissions. Design patterns are equally critical, which means the interview rewards candidates who can think in objects and state management, not just algorithm churn. String and trie show up in the harder problem, signaling you need to handle path parsing and hierarchical data. Sorting surfaces once but in context of file-system output. The difficulty split is punishing: one medium, one hard, no easy warm-up. Drill the bank system first to lock down hash-table state and simulation logic. Then move to the file system, where you'll need trie knowledge and careful string handling. If you blank on either design during the live assessment, StealthCoder solves it in real time while the proctor sees nothing.
Companies with similar patterns
If you prepped for Circle, these companies recycle ~60% of the same topics.
You've seen the list.
Now make sure you pass Circle.
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 an Amazon engineer who watched the leaked-problem repo become an industry secret. He decided you should have it too. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Circle interview FAQ
Should I study hash tables or design patterns first for Circle?+
Hash tables appear in both top problems, so they're non-negotiable. But hash tables alone won't get you past these interviews. Both problems require you to design classes, manage state, and simulate operations. Spend 60% on hash-table-backed design patterns, 40% on the raw data structure drills.
Is the Simple Bank System enough practice for Circle's medium problem?+
It's the reported medium, so yes, it's directly relevant. But it's also your baseline. The hard problem (file system) adds trie logic and path parsing. If you only solve the bank system, you're missing half the pattern. Do both to understand Circle's full scope.
How much time should I spend on the file system problem before my interview?+
The file system is hard and combines hash tables, tries, strings, and sorting. It's a time sink but essential. Aim to solve it end-to-end at least once, then drill the trie traversal and path-parsing logic separately. You need muscle memory on the trie part especially.
What if I freeze on design during the live assessment?+
That's exactly why StealthCoder exists. It reads your problem on screen and surfaces a working solution in seconds, invisible to the proctor. You copy the approach, adapt it live, and move forward. You don't get marked down for thinking time.
Should I learn tries before my Circle interview?+
Tries appear in the reported hard problem (file system). If you skip them, you're guessing on one of two problems. A quick trie primer is worth the hour. You need to understand insert, search, and hierarchical traversal for path handling.