Split Strings by Separator
A easy-tier problem at 75% community acceptance, tagged with Array, String. Reported in interviews at Coupang and 1 others.
Split Strings by Separator is an easy array and string problem that hits your assessment with a deceptive simplicity. Coupang and Apple both ask it. The acceptance rate sits at 75 percent, which means three-quarters of candidates solve it cleanly, but that 25 percent fail often on edge cases or overthink the built-in tooling. You'll get a list of strings, a separator character, and you need to split each string and filter out empty results. The trick is handling the separator correctly, especially when it appears consecutively or at boundaries. If you hit this live and blank on the exact method, StealthCoder surfaces a working solution in seconds while staying invisible to the proctor.
Companies that ask "Split Strings by Separator"
Split Strings by Separator 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 naive read is to call the built-in split method on each string and concatenate results. That works, but the catch is trailing separators and consecutive separators create empty strings you have to remove. Most candidates either forget the filter step or implement it inefficiently. The real pattern is understanding how your language's string-split behaves at boundaries. Some languages split on all occurrences and leave empties; others handle it gracefully. You also need to decide: do you filter before concatenating or after. The wrong choice tanks performance on large inputs. Edge cases kill people here: single-character separators, separators that don't exist in the string, strings that are only the separator, or empty input arrays. If you've drilled string manipulation, this is a sixty-second solve. If you haven't, you'll waste time debugging empty-string logic during your assessment. StealthCoder's hedge is knowing the exact filtering pattern for your language without having to test it live.
Pattern tags
You know the problem.
Make sure you actually pass it.
Split Strings by Separator 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.
Split Strings by Separator interview FAQ
Is this really just calling split() and filtering empties?+
Mostly yes, but the order matters. You split each string, then filter out empty strings from all results, then flatten into a single output array. The gotcha is that some languages' split leaves empties at boundaries; you can't rely on the method to clean that up. Read the problem constraints on what constitutes a 'valid' output string.
Why do Coupang and Apple ask this if it's easy?+
Easy doesn't mean trivial. It's a screening filter: solvers who understand string APIs and edge cases move forward. It also tests attention to detail. Candidates who rush and forget the empty-string filter fail even though the problem is conceptually simple. It's a 'do you code carefully' check.
What's the biggest edge case people miss?+
Consecutive separators or trailing separators creating empty strings in the result. If the input is 'a||b' with separator '|', you'll get ['a', '', 'b']. Most people forget to filter the empty string. Also test single-character and null/empty separator behavior in your language.
Should I worry about performance or just get it working?+
With 75 percent acceptance, most people are getting it working. But performance matters if input size is large. A single-pass filter is fine. Avoid nested loops or repeated string operations. Most languages' built-in split and filter are optimized; use them. Don't reinvent iteration.
How does this relate to the Array and String topics?+
It combines both. You're iterating over an array of strings (Array), and for each string you're calling string methods (String). The problem teaches you to be comfortable chaining operations across data types and understanding how each language's built-in APIs handle boundaries and empties.
Want the actual problem statement? View "Split Strings by Separator" on LeetCode →