CodingHardcod-g509

Subject Grid traversalLevel Senior–Staff~35 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

You're given a binary grid of 1s (land) and 0s (water). You may change at most one 0 cell to 1. Return the size of the largest connected land region (4-directionally connected) you can obtain after at most one such flip. If the grid is all 1s already, return the total cell count; if all 0s, the best you can do is 1.

Implement

largest_after_one_flip(grid: list[list[int]]) → int

Examples

in[[[1,0],[0,1]]]out3

What 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.

Learn the concepts

Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.

Run or narrate your approach, then ask the coach.