Zero Array Transformation III
A medium-tier problem at 55% community acceptance, tagged with Array, Greedy, Sorting. Reported in interviews at Microsoft and 1 others.
Zero Array Transformation III has shown up at Microsoft and Meta, and it's one of those medium-difficulty problems that looks straightforward until you're mid-interview and realize the greedy approach you coded doesn't handle the constraint edge cases. The 55% acceptance rate tells you plenty of people lock up here. This problem combines array manipulation with heap operations and prefix sum logic in a way that punishes the brute-force read first, ask questions later strategy. If this one hits your live assessment and you blank on the optimal ordering or the priority queue construction, StealthCoder surfaces the working solution in seconds, invisible to the proctor.
Companies that ask "Zero Array Transformation III"
Zero Array Transformation III 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 trick isn't obvious: you need to figure out the order in which to apply transformations, and a greedy heap-based approach with prefix sums lets you avoid simulating every step. The naive path is to apply operations left to right or try all permutations, both of which fail on time or miss the constraint structure. The real solution uses a priority queue to track which operations to apply when, combined with prefix sum logic to handle range updates efficiently without actually modifying the array each time. Most candidates get stuck choosing between sorting, heap priority, and the prefix sum layer. When you hit this live, the difference between 'I think I need a heap here' and 'I know exactly what the heap tracks and why the prefix sum order matters' is whether you're still coding at the 45-minute mark. StealthCoder is the hedge for the moment you realize you've been optimizing the wrong dimension.
Pattern tags
You know the problem.
Make sure you actually pass it.
Zero Array Transformation III 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.
Zero Array Transformation III interview FAQ
Is this problem actually asked at Meta and Microsoft, or is that just theoretical?+
Yes, both companies have reported it in their assessment pipeline. The 55% acceptance rate and medium difficulty suggest it's past the warm-up phase but not yet a rarity. It's the kind of problem that gets rotated in when they want to separate candidates who understand greedy optimization and heap mechanics from those who don't.
What's the core trick everyone misses on first read?+
Most candidates try to simulate the transformations directly, applying each operation and checking constraints in order. The real trick is realizing you need to sort or prioritize the operations using a heap, then use a prefix sum layer to avoid actually modifying the array. The order matters more than the brute-force logic.
Do I need to know all five topics listed, or is one dominant?+
Greedy and Heap are the core algorithmic pieces. Sorting sets up the greedy choice. Prefix Sum handles the range update logic without simulation. Array is just the data structure. You can't skip any of them, but Heap and Greedy are where you either get it or you don't.
How much time should I spend trying the greedy approach before switching gears?+
If your greedy choice doesn't let you justify why that operation should go first without simulating the entire array, stop. The correct greedy criterion is tied to the heap structure, not intuition. Spend 10 minutes on intuition, then pivot to understanding what the priority queue needs to track.
Is this one of those problems where the prefix sum feels like overkill?+
No. The prefix sum is how you avoid iterating through the array repeatedly. It's not decoration. Once you apply an operation, you mark it in the prefix sum layer, and subsequent range checks use that cumulative info. Without it, you're back to O(n^2) or worse.
Want the actual problem statement? View "Zero Array Transformation III" on LeetCode →