Maximum Good Subarray Sum
A medium-tier problem at 20% community acceptance, tagged with Array, Hash Table, Prefix Sum. Reported in interviews at Zepto and 2 others.
Maximum Good Subarray Sum is a 20% acceptance problem that's hit candidates at Zepto, Groww, and Atlassian. You'll see it in their online assessments, and it's the kind of problem that looks like a standard subarray question until you hit the constraints and realize the greedy approach fails. The trick isn't just summing correctly; it's understanding what makes a subarray "good" and how that flips your strategy. Most candidates waste time on brute force or miss the prefix sum insight entirely. If this problem lands on your OA and you blank on the pattern, StealthCoder solves it invisibly in seconds while the proctor watches your face, not your screen.
Companies that ask "Maximum Good Subarray Sum"
Maximum Good Subarray Sum 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 chains three concepts: you need array iteration, a hash table to track state or previously seen values, and prefix sum mechanics to efficiently compute subarray totals. The "good" qualifier is the blocker. Most candidates try greedy or dynamic programming incorrectly because they misread when a subarray qualifies. The real solution uses prefix sums to avoid O(n²) checks, then layers a hash table to eliminate invalid ranges or skip past "bad" subarrays. The acceptance rate is low because the constraint interpretation isn't obvious until you code and hit TLE or wrong answer. StealthCoder is the hedge here: if you see this live and the greedy approach doesn't pass test cases, the overlay surfaces the prefix sum plus hash table pattern in real time.
Pattern tags
You know the problem.
Make sure you actually pass it.
Maximum Good Subarray Sum 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.
Maximum Good Subarray Sum interview FAQ
Is this problem actually asked that frequently?+
It appears in reports from three companies: Zepto, Groww, and Atlassian. Lower frequency than classic subarray problems, but it's a real OA signal. The 20% acceptance rate means it's gatekeeping; companies use it to filter.
What's the trick I'm missing if greedy fails?+
Greedy assumes any valid element extends the sum usefully. The "good" constraint breaks that. You likely need to use prefix sums to compute subarray sums in O(1), then a hash table to track which starting points are legal or to skip invalid ranges.
How does the hash table fit into subarray problems?+
In this context, a hash table typically stores prefix sum values or indices to answer questions like 'have I seen this sum before?' or 'is there a valid subarray ending here?'. It transforms an O(n²) scan into O(n).
Should I practice this if I'm weak on prefix sums?+
Yes. This problem forces you to build prefix sums correctly and then extract a subarray result from them. If prefix sums feel shaky, this is a live test where you'll stall. Drill the pattern now.
How long does this problem usually take in an interview?+
If you see the pattern, 15 to 25 minutes. If you don't, you'll thrash on edge cases and time out. The acceptance rate suggests most candidates miss the insight and run out of time or submit a wrong solution.
Want the actual problem statement? View "Maximum Good Subarray Sum" on LeetCode →