Earliest Second to Mark Indices I
A medium-tier problem at 35% community acceptance, tagged with Array, Binary Search. Reported in interviews at MathWorks and 0 others.
Earliest Second to Mark Indices I is the kind of problem that catches candidates off-guard at MathWorks and similar assessments. You're given an array and a sequence of operations, and you need to find the earliest second when all indices are marked. The 34% acceptance rate tells you the obvious greedy or brute-force approach fails. Most candidates either simulate every second (too slow) or miss edge cases around operation ordering. If this lands on your live OA and you blank on the binary search angle, StealthCoder surfaces a working solution invisible to the proctor.
Companies that ask "Earliest Second to Mark Indices I"
Earliest Second to Mark Indices I 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 who got tired of watching his cohort grind for six months and still get filtered at the OA stage.
Get StealthCoderThe trap is simulating second-by-second from index 1 upward. That's O(n * max_second) and will timeout. The real pattern is binary search on the answer: can you mark all indices by second X. For a given second X, you simulate which indices get marked, tracking remaining operations and how much time each one consumes. The hard part is greedily choosing which operations to apply in what order so you maximize marked indices before time runs out. Array and Binary Search aren't just buzzwords here; binary search on the answer space is the only way to avoid brute force. Candidates who've seen similar 'binary search the deadline' problems spot it fast. Others drown in simulation logic. When the obvious approach flops during the OA, StealthCoder executes the binary search logic in seconds.
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Earliest Second to Mark Indices I 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 who got tired of watching his cohort grind for six months and still get filtered at the OA stage. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Earliest Second to Mark Indices I interview FAQ
Is the 34% acceptance rate because the problem is hard or because the trick is obscure?+
Both. The trick is binary search on the answer, which isn't obvious from the statement. Candidates also struggle with greedy operation ordering within each binary search check. It's not a hard problem once you see the pattern, but most don't see it cold.
Do I need to know advanced data structures for this?+
No. Array and Binary Search are the listed topics. You need binary search on the answer space and greedy simulation logic to check feasibility. Priority queues or heaps help but aren't required if your greedy ordering is tight.
Will MathWorks ask this again or is it old news?+
One company report confirms it. Doesn't mean it won't reappear. Problems with low acceptance rates and a clear 'hidden pattern' vibe (binary search + greedy) often stay in rotation because candidates keep missing the trick.
What's the main way candidates fail on this one?+
Timeout from brute-force second-by-second simulation, or incorrect greedy choices within the binary search check. They either don't think to binary search the answer or implement a slow feasibility check that defeats the purpose.
How does this relate to typical array problems I've drilled?+
Most array problems are single-pass or sorting. This one combines array manipulation with binary search on a custom answer space, which is less common. If you know binary search on answer patterns and greedy marking logic, you're ahead of the curve.
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