Find connected components in grid
Last updated: March 5, 2026
Quick Overview
Given a 2D grid consisting of 0s and 1s, where 1 represents land and 0 represents water, write a function to find and return the number of connected components of land in the grid. A connected component is defined as a group of adjacent 1s connected horizontally or vertically. The function should take the grid as input and output the count of distinct connected components.
Cockroach Labs
March 5, 2026148
15
1,926 solved
Given a 2D grid consisting of 0s and 1s, where 1 represents land and 0 represents water, write a function to find and return the number of connected components of land in the grid. A connected component is defined as a group of adjacent 1s connected horizontally or vertically. The function should take the grid as input and output the count of distinct connected components.
This coding problem is frequently asked during Technical Screen at Cockroach Labs. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Cockroach Labs expects candidates to write production-quality code, not just solve the puzzle.
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 iteratively instead of recursively (or vice versa)?
- Can you solve this in a single pass?
- How would you parallelize this solution?
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Problem Analysis
To solve the problem of finding connected components in a grid of 0s and 1s, we can utilize Depth-First Search (DFS) or Breadth-First Search (BFS) to explore each component of land (1s) in the grid. T...
Approach
- Initialize a count to zero for connected components.
- Iterate through each cell in the grid.
- If the cell is a '1' (land) and hasn't been visited, it indicates the start of a new com...
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