Valid Word
A easy-tier problem at 39% community acceptance, tagged with String. Reported in interviews at Expedia and 1 others.
Valid Word is deceptively simple on the surface but trips up candidates who miss the actual constraint. You see an easy string problem, assume a regex or basic validation loop, then realize the rule set is narrower than you thought. With a 39% acceptance rate, plenty of people are overthinking or misreading the spec. Expedia and UKG both ask it. If this lands in your assessment and you blank on the exact validation rules, StealthCoder surfaces the right approach in seconds, invisible to the proctor.
Companies that ask "Valid Word"
Valid Word 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 isn't algorithmic complexity. It's precision on what counts as valid. Most candidates write a general string validator and lose points on edge cases or misunderstood constraints. The problem forces you to be exact about character rules, apostrophe handling, or length requirements. Common pitfall: assuming alphanumeric is enough when the problem has stricter rules. Another: forgetting that single characters or strings with only punctuation fail silently in your head. The real work is parsing the problem statement carefully, not the code. If you hit this live and the rules don't click immediately, StealthCoder reads the full spec and delivers a clean solution that handles all cases, so you don't guess wrong.
Pattern tags
You know the problem.
Make sure you actually pass it.
Valid Word recycles across companies for a reason. It's easy-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.
Valid Word interview FAQ
Is this really easy level, or is the acceptance rate a lie?+
The 39% acceptance rate tells you people are either misreading the rules or missing edge cases, not that the algorithm is hard. Easy doesn't mean forgiving. The code itself is short, but precision on what valid means is everything. Read the spec three times before coding.
What's the fastest way to solve this without overthinking?+
Identify the exact character set allowed (letters, digits, apostrophes, etc.), write a single pass loop or regex that enforces all rules at once, then test boundary cases like empty strings, single chars, and punctuation-only inputs. Don't add logic incrementally.
Is this still asked at Expedia and UKG?+
Both companies are on the reported list. Interview patterns shift, but string validation problems are stable in assessments. If it appears, it's usually part of a screen to see if you handle constraints cleanly, not to test data structures.
How does Valid Word relate to other string problems?+
It's a pure validation problem, not a search or manipulation problem. You're checking membership in a defined set, not transforming or finding patterns. That changes your approach entirely from substring or regex matching drills.
What kills most people on this problem?+
Ambiguity on apostrophes (leading, trailing, consecutive, or mid-word only) and forgetting that an empty or whitespace-only string should be invalid. People also test valid cases but skip edge failures. Read error cases as carefully as valid ones.
Want the actual problem statement? View "Valid Word" on LeetCode →