How should I practice Days Until Poisoned Plants Stabilize?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Apple phone screen problems in FastPrep.

Is Days Until Poisoned Plants Stabilize associated with Apple?

FastPrep tags this as a Apple phone screen coding practice problem when the problem catalog has that company and stage context.

Days Until Poisoned Plants Stabilize

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Problem statement

A rectangular binary grid represents plants: 1 is poisoned and 0 is healthy. At the end of each day, every healthy plant with at least k poisoned neighbors becomes poisoned. The eight horizontally, vertically, and diagonally adjacent cells are neighbors.

All changes for a day are simultaneous. Return the number of days until a full day would produce no additional poisoned plants.

Function

daysUntilPlantsStabilize(grid: int[][], k: int) → int

Examples

Example 1

grid = [[1,0,0],[0,0,0],[0,0,0]]k = 1return = 2

The cells adjacent to the initial poison change on day 1, and the final distant cell changes on day 2.

Example 2

grid = [[1,0],[0,0]]k = 2return = 0

No healthy plant initially has two poisoned neighbors, so the grid is already stable.

Constraints

1 <= grid.length, grid[i].length <= 500.
Every cell is 0 or 1, and every row has the same length.
1 <= k <= 8.