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Count Connected Land Regions in a Grid Coding / DSA Interview

Given a 2D grid of land and water cells, count the number of distinct connected land regions, where cells are connected horizontally or vertically.

Practice in Interview Dashboard

1. Problem Statement

You are given a 2D grid where each cell is land (1) or water (0). Count the number of connected land regions, where connectivity is horizontal or vertical only.

2. Live Coding Format

Work in the provided coding workspace while explaining your decisions to the live interviewer. Validation may use inline tests, examples, comments, or a verbal walkthrough.

3. Key Focus Areas

  • 1
    Problem clarification and contract
  • 2
    Approach exploration and optimality
  • 3
    Think-aloud communication and pacing
  • 4
    Implementation correctness
  • 5
    Code quality and language fluency
  • 6
    Handwritten tests and dry run
  • 7
    Debugging and self-correction
  • 8
    Complexity analysis
  • 9
    Follow-up performance

4. What Strong Candidates Should Demonstrate

  • ✓Clarify adjacency rules and grid mutability before coding.
  • ✓Explain a naive re-scanning baseline and improve to a visited-tracking flood fill.
  • ✓Think aloud while implementing careful traversal and boundary checks.
  • ✓Validate with explicit expected outputs and a top-to-bottom handwritten dry run.
  • ✓Analyze time and space complexity and pace the easy core problem to leave room for a coding follow-up.

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Practice this problem in the live coding workspace while the interviewer probes your clarification, implementation, trade-offs, and validation.

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Core Concepts

Grid TraversalDFS/BFSConnected ComponentsComplexity Analysis

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