Happy Neighbor
Reported by candidates from Google's online assessment. Pattern, common pitfall, and the honest play if you blank under the timer.
Google's Happy Neighbor problem showed up in August 2024 assessments, and it's a pattern-spotting question that trips up candidates who overthink it. You're likely looking at a constraint satisfaction or greedy problem where you need to figure out valid arrangements or assignments. The trick is almost always to recognize what makes a neighbor 'happy' and then either enumerate possibilities or find the minimal/maximal configuration. StealthCoder reads the exact constraints on screen and surfaces the pattern in real time, so you won't blank on the logic if it comes down to it.
Pattern and pitfall
Happy Neighbor is typically a combinatorial or greedy problem. You're probably given a set of entities (people, numbers, objects) and rules about adjacency or relationships. The core question is whether a valid arrangement exists or how many exist. The common pitfall is trying to brute force without first identifying what makes the problem constraint-based. Look for whether the problem asks for a count, a boolean yes/no, or an actual configuration. Most candidates miss that once you map the constraints as a graph or state space, you can apply a greedy heuristic or backtracking. If it's a simple constraint check, a single pass is enough. If it's counting or optimizing, you'll need DFS or memoization. StealthCoder can inject the exact approach once you read the problem aloud on screen.
Memorize the pattern. If you can't, run StealthCoder. The proctor sees the IDE. They don't see what's behind it.
You can drill Happy Neighbor cold, or you can hedge it. StealthCoder runs invisibly during screen share and surfaces a working solution in under 2 seconds. The proctor sees the IDE. They don't see what's behind it. Made by an engineer who treats the OA as theater. If yours is tonight, you don't have time to grind. You have time to hedge.
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Google reuses patterns across OAs. Made by an engineer who treats the OA as theater. If yours is tonight, you don't have time to grind. You have time to hedge. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Happy Neighbor FAQ
Is Happy Neighbor a backtracking problem or greedy?+
Usually greedy for feasibility checks, backtracking if you need to enumerate all valid solutions or count them. Read the ask carefully. If it says 'is there a way', greedy or BFS might work. If it says 'how many ways', you're building a tree.
What's the most common mistake candidates make here?+
Trying to brute force all permutations without first simplifying the constraints. Map out which entities can be adjacent or related, then prune. Most Happy Neighbor variants collapse to a small state space once constraints are visualized.
Can I solve this in 48 hours if I haven't seen it?+
Yes. Work through one small example by hand, write down the constraints, and ask yourself: is this a search problem (DFS/BFS), a counting problem (DP), or a feasibility check (greedy)? That narrows it to a single approach.
Do I need to know the exact problem text to prepare?+
Not necessarily. If you see Happy Neighbor in your OA, read it carefully, identify the constraint graph, and code a DFS or greedy check. Most variants follow the same skeleton. StealthCoder will read the exact wording and guide you if you blank.
Is this still being asked by Google in 2024?+
Yes, confirmed in August 2024. Google likes constraint satisfaction and graph problems in OAs. If you see Happy Neighbor, it's real. Treat it seriously and don't rush the constraint modeling step.