Multi-source activation time
Given an R x C grid where each cell is 0 (empty), 1 (susceptible), or 2 (already activated), each minute every activated cell activates its 4-directionally adjacent susceptible cells simultaneously. Return the minimum number of minutes until no susceptible cell remains, or -1 if some susceptible cell can never be reached. If there are no susceptible cells initially, return 0.
Implement
spread_time(grid: list[list[int]]) → intExamples
in
[[[2,1,1],[1,1,0],[0,1,1]]]out4What a strong answer looks like
State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.
0:00 of about 25 min
solution.py
InputExpectedGot
[[[2,1,1],[1,1,0],[0,1,1]]]4not run yetsample