Graphs & Grids

Graphs show up regularly in Apple's coding rounds, and two problems carry most of the grid-and-graph cluster. Counting a Premium question in a grid is the top grid question by candidate reports, asked as the clean classic with no exotic twist. A Premium question, the question of whether a set of tasks with prerequisites can be ordered at all, recurs in the same loops. Both sit in the medium band that the loop lives in, so the bar is correct, tested code that handles its edges. A clever trick nobody has seen before earns no extra credit.

The two cluster together because each one is really a graph problem with the graph hidden behind the setup, and spotting it underneath is the only hard part. A grid of land and water is a graph where every cell connects to its four neighbors. A list of course prerequisites is a directed graph where an edge means "do this one first." One traversal pattern and one ordering pattern cover both. Once you know which graph the prompt hides, the only open question is which skeleton fits, and the rest is careful typing.