Maximal Rectangle
A hard-tier problem at 54% community acceptance, tagged with Array, Dynamic Programming, Stack. Reported in interviews at Huawei and 14 others.
Maximal Rectangle is a hard problem that shows up across Google, Amazon, Microsoft, Meta, and Bloomberg technical assessments. You're given a binary matrix and need to find the largest rectangle containing only 1s. The naive approach times out. The trick is reducing it to the Largest Rectangle in Histogram problem, applied row by row. If you haven't drilled the histogram pattern, this one bites hard. That's where StealthCoder becomes your safety net: if you blank on the stacking or height-array logic during the live OA, it surfaces a working solution in seconds, invisible to the proctor.
Companies that ask "Maximal Rectangle"
Maximal Rectangle 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 pattern most candidates miss is that you can treat each row as the base of a histogram. For each cell, track the height of consecutive 1s above it. Then solve Largest Rectangle in Histogram for that height array using a monotonic stack. The stack maintains increasing bar heights and pops when a shorter bar arrives, calculating area on the way. Common failures: forgetting to reset heights when you hit a 0, miscalculating area (width times height), or trying a brute-force 2D DP that blows up on large matrices. The monotonic stack is non-intuitive if you haven't seen it before. This problem combines Array, Dynamic Programming, Stack, and Matrix topics in ways that trip up candidates who studied them separately. StealthCoder handles the stack mechanics and height-array tracking so you don't lose points to implementation details.
Pattern tags
You know the problem.
Make sure you actually pass it.
Maximal Rectangle 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 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.
Maximal Rectangle interview FAQ
How hard is Maximal Rectangle really compared to other hard problems?+
At 53.7% acceptance, it's harder than average but not the top-tier wall. The difficulty is the pattern, not the code length. Most failures come from not knowing or forgetting the histogram reduction. Once you see it, it's mechanical. Practice Largest Rectangle in Histogram first.
Do Google and Amazon really ask this, or is it just a rep problem?+
It's reported by 10 top companies including Google, Amazon, Microsoft, and Meta. It's a genuine high-signal problem, not a leetcode artifact. It tests pattern recognition and DP thinking under pressure, which they care about.
What's the trick I'm missing if I try a 2D DP approach?+
A 2D DP for all subrectangles is O(m^2 * n^2) and times out. The insight is that you don't need 2D DP at all. Reduce each row to a 1D histogram and apply the linear histogram algorithm once per row. That's O(m * n) and passes.
Do I need to nail the monotonic stack, or can I use a simpler approach?+
The monotonic stack is the standard efficient solution for Largest Rectangle in Histogram (O(n) per row). A brute-force histogram check per row works but slower. For hard problems at FAANG scale, the stack version is expected. It's worth drilling.
If I see this live and blank on the pattern, what do I do?+
You're watching time drain on a hard problem you don't recognize. That's exactly when StealthCoder runs invisibly and shows you a working solution. You study the code, submit it, and move on. You don't fail because you didn't drill one specific pattern.
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