Maximum Palindromes After Operations
A medium-tier problem at 43% community acceptance, tagged with Array, Hash Table, String. Reported in interviews at MathWorks and 1 others.
Maximum Palindromes After Operations is a medium-difficulty problem that MathWorks and Grammarly have both asked. With a 43% acceptance rate, most candidates miss the greedy angle on the first attempt. You're given an array of strings and can perform operations, the goal is to maximize how many palindromes you can form. The trick isn't brute force. It's recognizing which operations to prioritize and which strings to leave alone. If you hit this live and freeze on the strategy, StealthCoder surfaces a working solution in seconds, invisible to the proctor.
Companies that ask "Maximum Palindromes After Operations"
Maximum Palindromes After Operations 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 core insight is greedy sorting and character-pairing logic. Most candidates start by trying to transform every string into a palindrome, but that's wasteful. The real move is to count available character pairs globally, then greedily assign them to strings that are close to palindromic, prioritizing strings that need the fewest operations. You'll need a hash table to track character frequencies across the input, then sort strings by transformation cost. Common failure points: attempting to optimize locally per-string instead of globally, or not realizing a single character in the middle can "anchor" a palindrome for free. If you didn't drill the greedy character-pairing pattern before your OA, StealthCoder hedges that gap by instantly showing the correct priority order and pair-counting logic.
Pattern tags
You know the problem.
Make sure you actually pass it.
Maximum Palindromes After Operations 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.
Maximum Palindromes After Operations interview FAQ
How do I know this is a greedy problem and not dynamic programming?+
The problem asks for a count or configuration that maximizes a global metric (total palindromes). DP would be overkill here. The greedy move is to sort strings by operation cost and assign available character pairs in that order. The 43% acceptance rate reflects candidates who overthink the state space.
What's the main trick I'm missing if I can't get past 'transform every string'?+
You're thinking locally. Build a global pool of character pairs from the entire array, then greedily pick which strings to convert based on how cheap they are to palindromize. Strings that are already close to palindromic (or have a unique center character) should go first.
Is this problem still asked at top companies?+
Yes. Both MathWorks and Grammarly have included it in their OAs. It's less common than classic string problems, but it appears in practical interview rotations, especially for roles focused on optimization and greedy algorithms.
How does this relate to the other topics like Array and Hash Table?+
Hash Table counts character frequencies across all strings (the global pool). Array logic sorts and iterates through strings by operation cost. Sorting ties it all together. You can't skip any of these topics to solve it cleanly.
What's the time complexity I should target?+
Linear or near-linear in the total number of characters across all strings, plus O(n log n) for sorting by cost. If you're sketching a solution that iterates multiple times over the entire array, you're likely not greedy enough. Reconsider what you can compute in a single pass.
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