String to Integer (atoi)
A medium-tier problem at 19% community acceptance, tagged with String. Reported in interviews at Niantic and 15 others.
String to Integer (atoi) has a deceptively low acceptance rate of 19%, which means most candidates who see it live either miss edge cases or overcomplicate the parsing logic. Meta, Microsoft, Amazon, Apple, and Uber all ask this, and it's the kind of problem that looks trivial on paper but punishes you for skipping the small print. The trick isn't the algorithm, it's handling whitespace, signs, overflow, and non-numeric characters correctly. If you freeze during your live assessment and can't remember the exact state machine flow, StealthCoder surfaces a bulletproof solution in seconds, invisible to the proctor.
Companies that ask "String to Integer (atoi)"
String to Integer (atoi) 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 because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround.
Get StealthCoderThe problem requires you to parse a string into a 32-bit integer while respecting leading whitespace, optional signs, and stopping at the first non-digit character. Most candidates attempt a naive scan-and-convert that works on clean input but fails on edge cases like leading spaces, multiple signs, or overflow boundaries. The real pattern is a simple state machine: skip whitespace, consume one sign, extract digits, and clamp to INT_MIN and INT_MAX. The 19% acceptance rate reflects how many people either implement this halfway or forget the clamping step entirely. String parsing under pressure is exactly where a real-time safety net pays off. If you haven't drilled this specific state machine before, StealthCoder solves it on demand when it appears in your OA.
Pattern tags
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String to Integer (atoi) 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 because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround. Works on HackerRank, CodeSignal, CoderPad, and Karat.
String to Integer (atoi) interview FAQ
Why is the acceptance rate so low for a problem labeled Medium?+
The low 19% acceptance reflects the hidden complexity in edge cases: leading spaces, plus/minus signs, integer overflow, and invalid trailing characters. Most solutions pass obvious test cases but fail on boundary conditions. It's Medium because the core logic is simple, but the rigor required to pass all tests is high.
Do companies like Meta and Microsoft really ask this in interviews?+
Yes. Meta, Microsoft, Amazon, Apple, and Uber all report asking this problem. It's popular because it tests both string handling and attention to detail. Candidates who skip it in prep often hit it live and run out of time debugging edge cases.
What's the main trick candidates miss?+
Overflow handling. Converting digit by digit and clamping the result to INT_MIN and INT_MAX before returning is the key. Many solutions skip this or check it after the fact, which fails when the intermediate value exceeds the 32-bit range.
Is this problem still asked frequently?+
Yes. It appears in reports from 16 major companies across hardware, gaming, finance, and cloud. Uber and Qualcomm include it in their assessments. It's a classic that doesn't age out because the pattern is fundamental.
How should I practice this before an OA?+
Write out the state machine on paper first: skip spaces, read sign, extract digits, clamp. Then code it without looking at solutions. Test against edge cases like ' -42', 'words and 987', '4193 with words', and boundary values. That rigor is what separates passes from failures.
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