CodingHardcod-g918

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

Question

Given an m x n binary grid, an island is a group of 1s connected 4-directionally. Two islands are considered the same if and only if one can be translated (shifted, not rotated or reflected) to equal the other. Return the number of distinct island shapes. The grid may be empty of land.

Implement

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

Examples

in[[[1,1,0,0,0],[1,1,0,0,0],[0,0,0,1,1],[0,0,0,1,1]]]out1

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.