Maximum Product of First and Last Elements of a Subsequence
A medium-tier problem at 30% community acceptance, tagged with Array, Two Pointers. Reported in interviews at KLA and 0 others.
You're looking at a medium-difficulty problem that KLA has actually asked. The acceptance rate is under 30%, which tells you the trick isn't obvious. You need to find a subsequence where the product of its first and last elements is maximized. The setup sounds simple, but most candidates start with a brute-force scan of all pairs and miss the structural insight that makes this solvable in linear time. If you hit this on a live OA and freeze, StealthCoder surfaces the working solution in seconds, invisible to the proctor.
Companies that ask "Maximum Product of First and Last Elements of a Subsequence"
Maximum Product of First and Last Elements of a Subsequence 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 trap is thinking you need to try every subsequence or every pair of indices. The actual pattern: use two pointers and track products as you contract the search space. You're not just pairing the first and last elements of the input array, you're choosing which elements to include in your subsequence, then multiplying the endpoints. The insight is that you can iterate through possible products by considering subarrays or by recognizing that negative numbers flip which endpoint is the maximum. Common failures happen because candidates don't account for negative products swinging the maximum when you move pointers inward. Array and Two Pointers are the stated topics, which means the solution exploits that contraction property. StealthCoder handles the edge cases and pointer logic that trap most people under time pressure.
Pattern tags
You know the problem.
Make sure you actually pass it.
Maximum Product of First and Last Elements of a Subsequence 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 Product of First and Last Elements of a Subsequence interview FAQ
Is this really a two-pointers problem or just dynamic programming?+
It's genuinely two-pointers. The trick is that when you move pointers inward, you're systematically covering all meaningful product pairs. DP is overkill and slower. Two pointers gives you O(n) with the right invariant tracking.
Do I need to consider negative numbers?+
Yes. Negatives are the entire reason this isn't trivial. A large negative times another negative becomes a large positive. You have to track max and min products as you move pointers inward, not just the absolute maximum.
Why is the acceptance rate so low if it's only medium difficulty?+
Because the two-pointer insight isn't taught in most algorithm curriculums. Candidates assume they need brute force or DP, hit time limits, and fail. Knowing the pattern cuts your solving time from 20 minutes to 5.
Will KLA ask this again or is it a one-off?+
One company in the data, but that doesn't mean it's rare. KLA is a specific hiring target for some tracks. The broader pattern (two pointers on products) appears in many OAs. Master the approach, not just this instance.
Should I practice array or two-pointers problems first to prep for this?+
Do two-pointers problems first. This problem is the intersection of both topics, but the two-pointer logic is what separates a 5-minute solve from a 30-minute failure spiral.
Want the actual problem statement? View "Maximum Product of First and Last Elements of a Subsequence" on LeetCode →