CodingMediumcod-p004

Subject GraphsLevel Mid–Senior~30 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

Given a grid of 1s (land) and 0s (water), count the number of islands. An island is a group of 1s connected horizontally or vertically.

Implement

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

Examples

in[[[1,1,0],[1,0,0],[0,0,1]]]out2

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.