Minimum Operations to Make a Uni-Value Grid
A medium-tier problem at 67% community acceptance, tagged with Array, Math, Sorting. Reported in interviews at EPAM Systems and 0 others.
You've got a grid where every cell needs to become the same value, and each operation changes an entire row or column by a fixed amount. EPAM Systems has asked this. It sounds straightforward until you realize the trick: you can't just pick any target value and work backwards. The insight is that all cells in the same diagonal have a fixed difference, and you need to find the target that minimizes total operations. With a 67% acceptance rate, this one punishes brute force. StealthCoder solves it in seconds if you freeze during your assessment.
Companies that ask "Minimum Operations to Make a Uni-Value Grid"
Minimum Operations to Make a Uni-Value Grid 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 core pattern: when you adjust rows and columns, the relative difference between two cells in the same diagonal (where row minus column is constant) never changes. So instead of trying every possible target value, you extract the relative differences, then find the target that minimizes the sum of absolute changes across all unique differences. Common failure: trying to find the 'best' row or column operation order and simulating. Actual solution: Math. You compute what each cell would be for a given target, find the median of required operations, and return the answer. Array, Matrix, Sorting, and Math all collide here. StealthCoder is your hedge if the diagonal-invariant insight doesn't click and you're burning time on simulation.
Pattern tags
You know the problem.
Make sure you actually pass it.
Minimum Operations to Make a Uni-Value Grid 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.
Minimum Operations to Make a Uni-Value Grid interview FAQ
Is this problem really just about grid simulation?+
No. Simulating all operations is too slow. The trick is that cells on the same diagonal have fixed relative differences. You don't simulate; you compute the optimal target value using Math and find the minimum cost. That's what separates accepted from timeout.
How do I know what target value to aim for?+
You don't guess. Extract the differences between each cell and its target, collect them, sort them, and find the median. The median minimizes the sum of absolute deviations. This applies to all affected diagonals at once.
Why is this asked at EPAM Systems?+
It tests whether you can recognize that a brute-force grid simulation is a trap and spot the Math insight instead. It's a medium-difficulty filter for algorithmic thinking, not implementation speed.
Do I need to touch every cell individually?+
No. Group cells by their row-column diagonal. Cells on the same diagonal will always have the same relative offset, so you work with unique diagonals, not the full grid.
What if I implement simulation and it times out?+
You've hit the intended pitfall. Back up, think about what properties are invariant under row and column operations, and recognize that you're really solving an optimization problem, not a simulation problem.
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