Rover Move
Reported by candidates from IBM's online assessment. Pattern, common pitfall, and the honest play if you blank under the timer.
IBM's Rover Move problem hit the assessment in September, and it's a simulation question dressed up in robotics language. You get a rover on a grid, a sequence of commands, and you need to track its position and direction as it moves. It sounds mechanical, but the actual trick is state management: keeping direction consistent as the rover rotates and moves. If you nail the coordinate system and command parsing upfront, the rest is just bookkeeping. StealthCoder catches the off-by-one errors and direction mixups when you're live and your brain stalls.
Pattern and pitfall
Rover Move is a pure simulation problem. The rover starts at an origin with a direction (N, S, E, W), and commands like L (left turn), R (right turn), and M (move forward) mutate its state. The gotcha is that rotate and move must be separate operations, and direction encoding matters. Most candidates either confuse coordinate axes (x vs row, y vs col) or mess up the rotation logic (mixing clockwise and counter-clockwise). Write a direction map that encodes N, E, S, W as integers 0-3, then use modulo arithmetic for turns. For movement, apply the direction to update coordinates cleanly. Test with a simple sequence first. StealthCoder is your safety net if you blank on the direction enum or rotation formula during the live OA.
If this hits your live OA and you blank, StealthCoder solves it in seconds, invisible to the proctor.
You can drill Rover Move 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 would have shipped this the night before his JPMorgan OA if he'd had it.
Get StealthCoderRelated leaked OAs
You've seen the question.
Make sure you actually pass IBM's OA.
IBM reuses patterns across OAs. Built by an Amazon engineer who would have shipped this the night before his JPMorgan OA if he'd had it. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Rover Move FAQ
Is this actually hard?+
No. It's tedious if you hardcode turns wrong, but straightforward if you model direction as a number. The real challenge is reading the problem carefully and not confusing yourself with axis notation. Most people solve it in 10-15 minutes once they start coding.
What's the most common mistake?+
Rotating the wrong direction or forgetting that L and R are relative to the rover's current heading. A lot of candidates also confuse rows/columns with x/y. Use a direction array (0=N, 1=E, 2=S, 3=W) and rotate with (direction + offset) % 4.
Do I need a matrix or grid data structure?+
Not necessarily. You only track one rover's position and direction. Use two variables for coordinates and one for direction. No need to build or store a grid unless the problem explicitly asks you to visualize it afterward.
What if there are multiple rovers?+
Same logic, but repeat for each rover. Each rover has its own (x, y, direction) state. Parse commands per rover, apply them in sequence, and output final positions. The pattern doesn't change, just the loop scope.
How do I prep in 48 hours?+
Write out a direction encoding (N=0, E=1, S=2, W=3). Practice a small manual trace: start at (0,0) facing N, run L, M, R, M. Code it. Test edge cases where rovers wrap or collide (if mentioned). That's it. Don't over-engineer.