Evaluate Reverse Polish Notation
A medium-tier problem at 55% community acceptance, tagged with Array, Math, Stack. Reported in interviews at Apollo.io and 12 others.
Evaluate Reverse Polish Notation is a classic medium-difficulty stack problem that trips up candidates who overthink it. You'll see it at Amazon, LinkedIn, Citadel, and seven other major companies. The acceptance rate sits around 55%, which means a significant chunk of people either blank on the stack pattern or botch the operator logic under pressure. If you hit this on an assessment and freeze on how to route operators versus operands, StealthCoder surfaces a working solution in seconds while staying invisible to the proctor.
Companies that ask "Evaluate Reverse Polish Notation"
Evaluate Reverse Polish Notation is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Built by an Amazon engineer who realized the OA tests how well you memorized 200 problems, not how well you code.
Get StealthCoderThe trick is recognizing that RPN is purpose-built for stack evaluation: operands go on, operators pop two, compute, push the result back. Most candidates get the structure right but fail on details: operator precedence (which doesn't exist in RPN, by design), integer division behavior (truncation toward zero, not floor), and handling negative numbers correctly. The naive approach of string parsing and type-checking is fine, but the logic around when to pop and push has to be airtight. Common failure points are off-by-one operator application, reversed operand order (does 3 - 5 mean '3 minus 5' or '5 minus 3'?), and not handling single-element edge cases. If you haven't drilled operator stacks recently and this pops up live, StealthCoder gives you the pattern and working code without breaking the assessment.
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Evaluate Reverse Polish Notation recycles across companies for a reason. It's medium-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Built by an Amazon engineer who realized the OA tests how well you memorized 200 problems, not how well you code. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Evaluate Reverse Polish Notation interview FAQ
Is this still asked at top companies like Amazon and LinkedIn?+
Yes. It appears across Amazon, LinkedIn, Citadel, and nine other companies in the data. The acceptance rate is 55%, so roughly half the candidates who attempt it don't pass. It's a canonical stack problem that interviewers trust to filter.
What's the trick to not reversing the operands?+
When you pop two values, the first pop is the second operand, the second pop is the first. So pop B, pop A, then compute A op B. Write it that way explicitly and the reversal trap vanishes.
How does this relate to parsing and why is Stack the core topic?+
Stack is the core because RPN is inherently stack-based notation. Parsing is the mechanics, but the conceptual insight is that stacks naturally handle operator precedence without parentheses or rules. That's why RPN exists.
What if I haven't studied Array, Math, and Stack together before?+
This problem sits at the intersection: you parse an array, use a stack data structure, and apply math operations. If you're weak on any one, the problem feels harder. Study stack fundamentals, operator precedence, and integer division edge cases as a unit.
Does integer division matter for the solution?+
Yes. Most languages truncate division toward zero, not floor. So -3 / 2 is -1, not -2. Check your language's behavior and handle it explicitly if needed. It's a common gotcha in the operator logic.
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