Brex coding interview
questions, leaked.
2 problems reported across recent Brex interviews. Top patterns: math, string, stack. The list below is what most reported candidates actually saw, plus the honest play if you can't grind all of it.
Brex's coding interview is lean but brutal. You're looking at two problems: one hard algorithmic challenge and one medium simulation. Basic Calculator III demands you parse and evaluate expressions with operators and parentheses in real time. Game of Life tests your ability to mutate state across a grid while tracking neighbors. The hard problem alone will eat most of your time. If you blank on expression parsing mid-assessment, StealthCoder runs invisibly and surfaces a working solution while the proctor sees nothing but your screen.
Top problems at Brex
| # | Problem | Diff | Frequency | Pass % | Patterns |
|---|---|---|---|---|---|
| 01 | Basic Calculator III | HARD | 0.0 | 52% | Math · String · Stack |
| 02 | Game of Life | MEDIUM | 0.0 | 71% | Array · Matrix · 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 Brex OA. The proctor cannot see it. Screen share cannot detect it. Built by an Amazon engineer who used it to pass JPMorgan's OA and system design loop.
Get StealthCoderBrex doesn't spread problems across ten topics. They're concentrated. Math and string handling collide in Calculator III, where recursion and stack manipulation are non-negotiable. Game of Life forces you to think in 2D coordinates and state transitions, not just iterate and print. Your prep order is fixed: nail expression parsing and recursion first, then drill the simulation logic for grid problems. The hard problem is the real filter. Calculator III requires you to handle nested parentheses, operator precedence, and multi-digit numbers simultaneously. Most candidates fail on precedence or get lost in the recursion. Game of Life is medium but unforgiving if you miss a neighbor-counting edge case. StealthCoder is your hedge for whatever pattern you didn't fully internalize before the live assessment.
Companies with similar patterns
If you prepped for Brex, these companies recycle ~60% of the same topics.
You've seen the list.
Now make sure you pass Brex.
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 Amazon engineer who used it to pass JPMorgan's OA and system design loop. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Brex interview FAQ
Should I spend more time on the hard problem or the medium one?+
The hard problem, Calculator III, is the real interview. It tests deeper algorithmic thinking and will determine pass or fail. Game of Life is the confirmatory problem. If you can't parse and evaluate expressions under pressure, you won't pass. Spend 70% of your prep on expression parsing and recursion.
What's the minimum I need to know about stacks for Brex?+
Everything. Calculator III lives on stacks. You need to know how to push operators, handle precedence, and use a stack to evaluate postfix expressions. Also understand when to recurse instead of iterating. Both approaches appear in solutions.
Is Game of Life really just iteration and counting neighbors?+
Not quite. The trap is in-place mutation. You can't modify the grid while reading it. Most candidates fail because they overwrite values before processing all neighbors. Use a copy or encode old and new state in a single cell. That's the real test.
How much of the interview is math versus string handling?+
They're tied together in Calculator III. You parse the string, perform math operations, and manage state with a stack. You can't separate them. If you're weak on either, you'll stall on the hard problem.
What if I run out of time and haven't solved Calculator III?+
You'll want Game of Life solved to show you can handle matrix logic. But Calculator III is weighted harder. If time is tight, get a brute-force or partial solution to the hard problem and complete the medium one fully. Partial credit on the hard problem beats perfect credit on medium alone.