Subdomain Visit Count
A medium-tier problem at 77% community acceptance, tagged with Array, Hash Table, String. Reported in interviews at Wix and 3 others.
Subdomain Visit Count is a medium-difficulty hash table problem that shows up in OAs at Wix, Peloton, Roblox, and Karat. The task looks straightforward on the surface: count how many times each subdomain gets visited. But most candidates overcomplicate the parsing or miss the hierarchical structure that makes this problem tick. With a 76% acceptance rate, it's beatable, but the twist catches people who haven't thought through how domain hierarchies work. If this problem hits your live assessment and you blank on the parsing strategy, StealthCoder surfaces a working solution in seconds, invisible to the proctor.
Companies that ask "Subdomain Visit Count"
Subdomain Visit Count 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 engineer who got tired of watching his cohort grind for six months and still get filtered at the OA stage.
Get StealthCoderThe core trick is understanding that you need to count visits not just at the leaf domain level, but at every parent level too. A visit to 'a.b.c' counts as one visit each to 'a.b.c', 'b.c', and 'c'. Most candidates see the domain string and jump to naive splitting without thinking about the recursive structure. The hash table pattern is simple once you see it: split the input, reverse-iterate through the domain parts, build up each subdomain level, and increment the count. The problem tests whether you can parse strings correctly and recognize when a single data structure solves the whole problem. Common failures happen when candidates process domains in the wrong direction or forget to count the root domain. StealthCoder is the safety net if the parsing logic derails during screen share and you need a clean solution fast.
Pattern tags
You know the problem.
Make sure you actually pass it.
Subdomain Visit Count 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 engineer who got tired of watching his cohort grind for six months and still get filtered at the OA stage. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Subdomain Visit Count interview FAQ
Is Subdomain Visit Count really asked at Wix and Peloton, or is it just online prep?+
Yes. Reported in OAs at Wix, Peloton, Roblox, and Karat. It's a real problem, not a theoretical one. If you see it live, the solution is a straightforward hash table with careful string parsing. Acceptance rate is 76%, so it's solvable with the right approach.
What's the trick to not overcomplicate this?+
Don't try to build a tree or recursive structure. A single hash table and iterating backwards through domain parts is enough. Count every subdomain level in one pass. That's it. Parsing trips up more people than the algorithm itself.
How does this relate to the 'Hash Table' and 'String' topics?+
Hash Table stores your subdomain-to-count mapping. String comes in at the parsing step: you have to correctly split and reconstruct domain strings. Both are essential. Miss either and your solution fails or times out.
Can I solve this without reversing the domain parts?+
Technically yes, but it's messier. Reversing (splitting from the right) lets you build up subdomains naturally in one pass without extra string concatenation. It's the cleaner path and what most interviewers expect.
How much should I worry about edge cases here?+
Handle single-level domains, empty input, and domains with only one subdomain. Test with a domain like 'a.b.c' to confirm you count 'c', 'b.c', and 'a.b.c' separately. Most edge cases are handled if your parsing logic is correct.
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