Make Array Empty
A hard-tier problem at 25% community acceptance, tagged with Array, Binary Search, Greedy. Reported in interviews at Zepto and 0 others.
Make Array Empty is a hard problem that's started appearing in live OAs at faster-growth companies like Zepto. Only about 25% of candidates solve it, which usually means there's a trick that separates the ones who see it from the ones grinding brute force. The problem sits at the intersection of sorting, greedy choice, and efficient range queries. If you hit this during an assessment and the obvious approach times out, you're not alone. This is exactly where StealthCoder runs invisibly and surfaces a working solution while you stay in control.
Companies that ask "Make Array Empty"
Make Array Empty 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 thinking you can simulate the process naively. Most candidates try to repeatedly scan the array and remove elements, which collapses into O(n squared) or worse. The actual insight: sort the elements with their original indices, then greedily decide which to remove based on what's already gone. Binary search, Binary Indexed Tree, or Segment Tree enter the picture when you need fast range queries to track which indices are still alive. The greedy + efficient lookup combo is what breaks the naive approach. The problem demands you think about state differently than it's presented. That reframe is the hard part. StealthCoder handles the implementation details if the pattern clicks but the code doesn't land fast enough.
Pattern tags
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Make Array Empty recycles across companies for a reason. It's hard-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.
Make Array Empty interview FAQ
Is Make Array Empty still asked at companies like Zepto?+
Yes. Zepto is listed in the company data for this problem. It's hard-tier, so you'll see it in final-round or system-design adjacent rounds. The 25% acceptance rate suggests it's a strong differentiator, not a throwaway.
What's the trick I'm missing if brute force times out?+
The naive simulation (find, remove, repeat) is O(n squared). The trick: sort elements by value with indices intact, then process greedily while tracking which indices are still active. A Binary Indexed Tree or Segment Tree answers 'how many elements before index X are still alive' in log time.
Do I need Binary Indexed Tree or can I use Binary Search?+
Binary Search on sorted values can work if you're careful about index mapping. Binary Indexed Tree or Segment Tree is cleaner for range queries. The problem lists all three as valid topics, so the intended solution likely leans on one of the tree structures.
How does sorting help if the problem says array order matters?+
The order matters for figuring out when elements are removed, not for the decision logic itself. Sorting by value lets you process removals in a sensible order while tracking original indices separately. That decoupling is the core insight.
Will studying just Array and Greedy topics prepare me?+
Partially. You need the greedy intuition, but the hard part is the efficient lookup on indices. Study Greedy + Binary Search or Binary Indexed Tree together. The problem pulls from multiple topics for a reason.
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