Cleaning Bot (Microsoft India)
Reported by candidates from Microsoft's online assessment. Pattern, common pitfall, and the honest play if you blank under the timer.
You're facing Microsoft India's Cleaning Bot question in March 2024, and the problem text isn't fully public yet. This is a simulation or state-based problem where you track a bot's movement or cleaning state across a grid or sequence. The tricky part is usually managing direction changes, boundary conditions, or detecting when the bot gets stuck in a loop. StealthCoder can read the exact problem when you're live and surface the core pattern in seconds, so you're not rebuilding logic under pressure.
Pattern and pitfall
Cleaning Bot problems typically require you to simulate movement with turn/forward commands, track visited cells, and identify termination conditions. The common trap is off-by-one errors in grid bounds, or missing the loop-detection logic that tells you when the bot will never finish. You'll likely need a set or hash table to track visited positions with direction state. The pattern feels like simulation but hinges on recognizing when simulation can stop. When you're live in the OA, if the problem statement is dense or you blank on the termination logic, StealthCoder will show you the exact pattern and a working skeleton so you can fill in coordinates and boundary checks without panicking.
If you see this problem in your OA tomorrow, the play is to recognize the pattern in 30 seconds. StealthCoder buys you that recognition.
You can drill Cleaning Bot (Microsoft India) 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. Built by an Amazon engineer who passed his OA cold and still thinks the filter is broken.
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Microsoft reuses patterns across OAs. Built by an Amazon engineer who passed his OA cold and still thinks the filter is broken. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Cleaning Bot (Microsoft India) FAQ
Is this a brute-force simulation or do I need dynamic programming?+
It's simulation with loop detection. You don't need DP. Track position and direction in a set, run the bot step by step, and return the cleaned count when you hit a visited state twice or go out of bounds. That's the full algorithm.
What's the main gotcha Microsoft usually includes?+
Detecting cycles correctly. The bot can get stuck spinning in place or looping a larger pattern. You need to store (x, y, direction) as your state tuple, not just (x, y). Missing the direction causes false negatives.
How do I handle the grid boundaries?+
Check bounds before moving. If a forward command would go out of bounds, the bot stays in place (most common rule). Some versions have walls. Read the problem statement carefully on this point because it changes the logic significantly.
Should I use a 2D array or a hash table for visited cells?+
Hash table (set of tuples) is cleaner and doesn't require knowing grid size upfront. If the problem gives you an explicit grid, either works, but a set is safer for large or unknown grid sizes.
Can I solve this in 10-15 minutes if I see it live?+
Yes, if you recognize the simulation pattern. Parse commands, loop through them, track state, detect cycles. The code is maybe 20-30 lines. The 80% win is knowing to store direction as part of state.