Max Area of Island
A medium-tier problem at 73% community acceptance, tagged with Array, Depth-First Search, Breadth-First Search. Reported in interviews at Grubhub and 13 others.
Max Area of Island is a medium-difficulty grid problem that shows up across 14 companies including Grubhub, Disney, Dropbox, TikTok, and Tesla. It looks simple on the surface: given a 2D matrix of land and water, find the largest contiguous island by area. The catch is that most candidates either pick the wrong traversal strategy, miss diagonal adjacency rules, or blow the time limit with inefficient marking. You'll see it in 73% of submissions succeed, but that's because many test cases are small. Scale it up and careless implementations timeout. If this problem hits your live assessment and you blank on the optimal approach, StealthCoder runs invisibly and surfaces a working solution in seconds.
Companies that ask "Max Area of Island"
Max Area of Island is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Built because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround.
Get StealthCoderThe core trick: you need to explore every connected component of land cells and track the maximum size. DFS or BFS both work, but you must mark visited cells in-place (or with a set) to avoid counting the same cell twice. The trap is thinking you need Union Find when simple traversal is faster. Another common miss: assuming diagonal cells connect (they don't in this variant). Implement your traversal cleanly, recursively or with a queue, and sum the area as you explore each island. The time complexity is O(rows * cols) and space is O(rows * cols) for the recursion stack or queue. On a live OA, the problem statement may try to confuse you with wording like 'connected component' or 'perimeter', read carefully. StealthCoder hedges the moment you realize your first approach is wrong mid-assessment.
Pattern tags
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Make sure you actually pass it.
Max Area of Island recycles across companies for a reason. It's medium-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Built because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Max Area of Island interview FAQ
Is Max Area of Island still asked at FAANG, or is it too easy now?+
It's active across 14 major companies, from Disney to TikTok to Tesla. The acceptance rate (73%) might seem high, but that reflects small test cases. Scale and follow-ups (like perimeter or counting islands) are where depth matters. It's a warm-up problem that filters quickly.
Should I use DFS or BFS for this problem?+
Either works fine for a single island. DFS is simpler to code (recursive, no queue needed), BFS is iterative and avoids stack overflow on huge grids. If the grid is bounded (e.g., 50x50), DFS wins on simplicity. If you're unsure mid-interview, start with DFS and mention you'd switch if recursion depth became an issue.
What's the difference between this problem and Union Find?+
Union Find is overkill here. It shines when you need to query connectivity or merge components dynamically. For a single pass to find max island area, DFS or BFS is faster and uses less memory. Save Union Find for union-heavy follow-ups or constraint-satisfaction variants.
How do I avoid counting the same cell twice?+
Mark visited cells immediately when you enter them, not when you exit. Use a separate 'visited' 2D array or a set, or overwrite the input grid (if allowed). The moment you step into a cell during DFS or BFS, mark it. Common pitfall: marking after processing, which leads to revisits and wrong area counts.
What topics from the input align with this problem?+
All five: Array (the grid is a 2D array), DFS and BFS (the traversal strategies), Union Find (an alternative approach, though suboptimal), and Matrix (the problem domain). Mastering DFS or BFS here unlocks similar grid problems (e.g., Surrounded Regions, Number of Islands). Arrays are just the data structure.
Want the actual problem statement? View "Max Area of Island" on LeetCode →