Maximum Number of Occurrences of a Substring
A medium-tier problem at 53% community acceptance, tagged with Hash Table, String, Sliding Window. Reported in interviews at Hubspot and 3 others.
Maximum Number of Occurrences of a Substring shows up in technical rounds at Hubspot, Roblox, Atlassian, and Salesforce. On the surface it sounds like a substring-search problem, but the trick isn't about finding all occurrences, it's about recognizing that only certain substrings are worth tracking at all. Most candidates burn 15 minutes chasing a brute-force approach before realizing the constraint that saves them. Acceptance sits at 53%, which means half the people who attempt it walk away empty-handed. If this problem hits your live assessment and you blank on the optimization, StealthCoder solves it in seconds, invisible to the proctor.
Companies that ask "Maximum Number of Occurrences of a Substring"
Maximum Number of Occurrences of a Substring 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 at a top-10 tech company who can solve these problems cold but didn't want to trust himself in a 90-minute screen share.
Get StealthCoderThe problem hinges on a mathematical constraint hidden in the input. Once you see it, you can rule out the vast majority of substrings without ever inspecting them. The real work is a single pass with a sliding window and hash table to count only the viable candidates. Most first attempts try to find every possible substring and check frequency, which balloons complexity fast. The winning approach compresses the search space so dramatically that the solution becomes nearly trivial. Hash tables hold your running counts, the sliding window keeps you honest about length, and you're done. The gap between 'I tried a nested loop solution' and 'I realized the constraint' is exactly where candidates fail. StealthCoder is your hedge when you're 10 minutes in and haven't spotted the optimization that makes this medium-difficulty instead of hard.
Pattern tags
You know the problem.
Make sure you actually pass it.
Maximum Number of Occurrences of a Substring 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 at a top-10 tech company who can solve these problems cold but didn't want to trust himself in a 90-minute screen share. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Maximum Number of Occurrences of a Substring interview FAQ
Is this really asked at Salesforce and Hubspot?+
Yes. All four companies in the input data have reportedly asked it. Acceptance rate of 53% suggests it's vetted and used, not a one-off question. It's not a classic (like Two Sum), but it's legitimate enough that candidates should know the pattern.
What's the trick I'm missing if I try nested loops?+
There's a mathematical constraint in the problem that eliminates most substrings from consideration before you even start counting. Once you identify that constraint, you only track a tiny subset of candidates. Nested loops mean you're checking everything, which is inefficient once you know better.
Does this require advanced string algorithms like KMP or Z-algorithm?+
No. Hash Table and Sliding Window (the two core topics) are sufficient. You don't need regex or fancy string matching. A simple hash table to count frequencies and a two-pointer window to iterate is the intended path.
How does this relate to the sliding window topic?+
Sliding window keeps your substring window at the right size and lets you scan in one pass. It prevents you from recalculating the same substring multiple times. Pair it with a hash table to store counts of valid windows, and you're golden.
If I haven't seen this pattern, can I still pass?+
Possibly, but only if you spot the constraint quickly. The 53% acceptance suggests a decent chunk of people solve it without prior drilling. But if you blank on the optimization, your interview time evaporates. That's where StealthCoder acts as insurance during the live OA.
Want the actual problem statement? View "Maximum Number of Occurrences of a Substring" on LeetCode →