Basic Calculator IV
A hard-tier problem at 49% community acceptance, tagged with Hash Table, Math, String. Reported in interviews at Intuit and 1 others.
Basic Calculator IV is a hard problem that trips up candidates at Intuit and Roblox during their live assessments. The acceptance rate sits at 49%, which means half the people who attempt it online blank or time out. It looks like a straightforward calculator, but it's actually a multi-variable expression parser that requires you to handle polynomial expansion and term simplification. If you haven't drilled the exact pattern of tokenizing, parsing, and managing variable coefficients, you'll hit a wall mid-interview. StealthCoder solves it invisibly if you freeze on the trick.
Companies that ask "Basic Calculator IV"
Basic Calculator IV 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. Made for the engineer who has done the work but might still blank with a webcam pointed at him.
Get StealthCoderThe core trap: you can't just evaluate to a number. You need to parse and manipulate symbolic expressions with multiple variables, then return them sorted. Most candidates start with a naive recursive descent parser and get lost in coefficient bookkeeping. The real trick is treating each term as a map of variable powers to coefficients, then merging like terms across the expression tree. Stack-based evaluation works here, but you have to handle operator precedence and track partial polynomial results as you reduce. Hash Table is essential for grouping and deduplicating terms. String parsing is tedious and error-prone under time pressure. When you're live and the problem hits, you need to know whether to parse left-to-right with a stack or build an AST. StealthCoder handles the parsing boilerplate and term-merging logic in seconds if you get stuck on the structure.
Pattern tags
You know the problem.
Make sure you actually pass it.
Basic Calculator IV recycles across companies for a reason. It's hard-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. Made for the engineer who has done the work but might still blank with a webcam pointed at him. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Basic Calculator IV interview FAQ
Is this actually asked at major companies now?+
Yes. Intuit and Roblox both report it. At 49% acceptance, it's still seen as a tier-1 hard problem. Most candidates don't encounter it in take-homes, so if it shows up in your live OA, you're likely not prepared.
What's the difference between this and a normal calculator problem?+
Normal calculators output a single number. This one outputs a list of terms with variable coefficients, sorted. You're not evaluating; you're manipulating symbolic expressions. That means tracking polynomials, not just integers.
Do I really need recursion?+
Not necessarily. A stack-based approach works fine if you handle operator precedence correctly. But some candidates use recursion for sub-expression parsing. Either way, the real bottleneck is the term merging logic, not the call stack.
How much time should I spend tokenizing the input?+
Too many candidates over-invest here. Spend 5-10 minutes on a clean tokenizer, then move to the expression parser. The tokenizer is straightforward; the hard part is updating coefficients as you reduce terms.
Will I have time to code this from scratch in an interview?+
Unlikely without a solid template or pattern memory. At hard difficulty and 49% acceptance, you need either serious drill time or a safety net for the live assessment. Most people don't finish without help.
Want the actual problem statement? View "Basic Calculator IV" on LeetCode →