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This is a medium difficulty Coding & Algorithms question, commonly asked during Technical Screen rounds at Snapchat.

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This question is commonly asked for Software Engineer candidates at Snapchat during technical interviews.

Find Maximum Island Perimeter | Snapchat Coding Question

Quick Overview

This question evaluates grid traversal and connected-component analysis skills, focusing on reasoning about perimeters and boundary conditions in binary matrices.

medium
Snapchat
Coding & Algorithms
Software Engineer

Find Maximum Island Perimeter

Company: Snapchat

Role: Software Engineer

Category: Coding & Algorithms

Difficulty: medium

Interview Round: Technical Screen

You are given an `m x n` binary grid where `1` represents land and `0` represents water. An island is a group of land cells connected vertically or horizontally. For each island, define its **perimeter** as the number of land edges that touch either water or the boundary of the grid. Return the **maximum perimeter** among all islands in the grid. If the grid contains no land, return `0`. You may solve this using either DFS or BFS. Example: - Input: ``` [ [1,1,0,0], [1,0,0,1], [0,0,1,1] ] ``` - Output: `8` Because the island with the largest perimeter has perimeter 8.

Quick Answer: This question evaluates grid traversal and connected-component analysis skills, focusing on reasoning about perimeters and boundary conditions in binary matrices.

You are given an m x n binary grid where 1 represents land and 0 represents water. An island is a group of land cells connected vertically or horizontally. The perimeter of an island is the total number of land edges that touch either water or the boundary of the grid. Return the maximum perimeter among all islands in the grid. If the grid contains no land, return 0. You may solve this problem using either DFS or BFS.

Constraints

0 <= m, n <= 200
grid[i][j] is either 0 or 1
Cells are connected only vertically and horizontally

Examples

Input: ([[1,1,0,0],[1,0,0,1],[0,0,1,1]],)

Expected Output: 8

Explanation: There are two islands, and both have perimeter 8, so the maximum perimeter is 8.

Input: ([[0,0],[0,0]],)

Expected Output: 0

Explanation: There is no land in the grid, so the answer is 0.

Input: ([],)

Expected Output: 0

Explanation: An empty grid contains no islands.

Input: ([[1]],)

Expected Output: 4

Explanation: A single land cell has all 4 sides exposed.

Input: ([[1,1,1],[1,0,1],[1,1,1]],)

Expected Output: 16

Explanation: The island surrounds a water cell. The outer boundary contributes 12 and the inner hole contributes 4, for a total of 16.

Input: ([[1,0,1,1],[1,0,1,0],[1,0,1,0]],)

Expected Output: 10

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Quick Overview

Find Maximum Island Perimeter

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