3 articles
Compute the minimum minutes for rot to spread across a grid using multi-source BFS. The canonical "all sources start at the same time" pattern that solves dozens of grid-spreading problems.
For each cell, return the distance to the nearest 0. Multi-source BFS from every 0 simultaneously gives the answer in linear time — the gold-standard pattern asked at every FAANG company.
Find the water cell whose distance to the nearest land is maximized. Multi-source BFS from all land cells gives the answer in linear time — a top FAANG distance-spread problem.