Find the Substring With Maximum Cost
A medium-tier problem at 57% community acceptance, tagged with Array, Hash Table, String. Reported in interviews at josh technology and 0 others.
Find the Substring With Maximum Cost is a medium-difficulty problem that's been asked at Josh Technology. With an acceptance rate around 57%, it sits in that annoying middle ground where the obvious greedy approach doesn't work, but the DP pattern isn't immediately obvious either. This is exactly the kind of problem you blank on during a live assessment, then realize the trick was clean the whole time. If you hit this in your OA and can't lock down the state transitions fast enough, StealthCoder surfaces a working solution invisible to the proctor.
Companies that ask "Find the Substring With Maximum Cost"
Find the Substring With Maximum Cost 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 trap here is assuming you can greedily pick high-cost substrings without overlap. The actual challenge is dynamic programming: for each position, you track the maximum cost you can achieve up to that point, then decide whether to extend the current substring or start fresh. You'll need to reason about how substring costs interact with character-to-cost mappings (likely stored in a hash table), and where it makes sense to break a substring vs. extend it. Common failure mode is mismanaging the state transitions or forgetting to handle the case where not including a character at all is optimal. During a timed OA, this state design takes mental bandwidth you don't always have. That's where StealthCoder becomes your safety net: you get the exact DP recurrence and implementation in seconds, no panic.
Pattern tags
You know the problem.
Make sure you actually pass it.
Find the Substring With Maximum Cost 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 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.
Find the Substring With Maximum Cost interview FAQ
Is this problem as common as other DP problems at FAANG?+
It's less frequent. Only Josh Technology appears in the data so far, suggesting this is more niche than classic DP hits like house robber or coin change. But it still shows up, and the pattern (substring optimization with state tracking) is portable to other interview rounds.
What's the actual trick to solving this efficiently?+
Dynamic programming where dp[i] = max cost achievable up to index i. The key insight: at each position, you either extend a substring or reset. The trick is correctly computing the cost of each candidate substring using the character-to-cost hash table without re-iterating.
How does this relate to Array and Hash Table topics?+
You iterate the array (Array), use a hash table to map characters to costs in O(1), and track the best result so far. The hash table lookup is critical for efficiency. Without it, you'd degrade to quadratic time.
Why is the acceptance rate only 57% for medium difficulty?+
The DP state design isn't obvious. Candidates often confuse when to break vs. extend substrings, or implement a greedy approach that fails on test cases with overlapping cost regions. Under time pressure, the logic is easy to botch.
Should I practice this before a Josh Technology OA?+
If you're in Josh Technology's pipeline, yes. If not, it's a solid DP pattern to know but lower priority than classic house robber or DP on strings. Either way, StealthCoder is your hedge if it appears live and you blank on the state transition.
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