Find connected components in grid
Last updated: February 19, 2026
Quick Overview
Given a 2D grid consisting of 0s and 1s, where 1s represent land and 0s represent water, write a function to find all connected components of land in the grid. A connected component is defined as a group of adjacent 1s that are connected horizontally or vertically. The function should return a list of lists, where each inner list contains the coordinates of the cells that make up a connected component.
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Given a 2D grid consisting of 0s and 1s, where 1s represent land and 0s represent water, write a function to find all connected components of land in the grid. A connected component is defined as a group of adjacent 1s that are connected horizontally or vertically. The function should return a list of lists, where each inner list contains the coordinates of the cells that make up a connected component.
LinkedIn uses this problem in the Take-home Project to evaluate your algorithmic thinking. They expect you to discuss multiple approaches, analyze trade-offs between them, and implement the optimal solution with clean, readable code.
What the Interviewer Expects
- Identify the correct data structure and algorithm for the problem
- Write clean, bug-free code with proper variable naming
- Analyze time and space complexity correctly
- Handle basic edge cases (empty input, single element)
- Communicate your thought process while coding
Key Topics to Cover
How to Approach This
- Clarify input constraints and edge cases before writing code.
- Walk through your approach verbally and confirm with the interviewer before coding.
- Start with a brute force solution, then optimize. Mention time and space complexity.
- Test your solution with examples, including edge cases like empty input or duplicates.
- Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
- Can you optimize the space complexity of your solution?
- Can you solve this in a single pass?
- How would you parallelize this solution?
- What if the input doesn't fit in memory?
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Practice DSA ProblemsSample Answer
Problem Analysis
In this problem, we need to identify all connected components of land (1s) in a 2D grid where connections are made through adjacent cells (up, down, left, right). The two-pointer technique or Depth-Fi...
Approach
We will utilize a Depth-First Search (DFS) algorithm to traverse the grid and identify connected components. Here’s the step-by-step approach:
- Initialize an empty list
componentsto store the con...
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