Faulty Keyboard
A easy-tier problem at 79% community acceptance, tagged with String, Simulation. Reported in interviews at Samsung and 0 others.
You're staring at a keyboard problem on your Samsung phone interview and thinking it's trivial. Don't underestimate it. Faulty Keyboard is asked in real assessments, and the 78.6% acceptance rate masks a common trap: candidates overthink string manipulation when the real work is parsing which character caused backspace chaos. The problem feels straightforward until you hit the edge cases on live video. If you blank on the simulation logic under pressure, StealthCoder runs invisibly and hands you a working solution in seconds, so you move on instead of drowning.
Companies that ask "Faulty Keyboard"
Faulty Keyboard 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 by an Amazon engineer who used it to pass JPMorgan's OA and system design loop.
Get StealthCoderThe trick here is understanding that a backspace doesn't just delete the character before it in the output string, it deletes whatever was actually typed before, even if that character was also deleted by an earlier backspace. Most candidates try to process the string left-to-right and handle backspaces as they encounter them, but the simulation breaks if you don't track state correctly. The pattern is this: iterate through the input, maintain a result string or stack, and when you hit a backspace character, pop from your result if it's not empty. It sounds basic until you test on strings with consecutive backspaces or backspaces at the start. The simulation approach isn't about algorithmic genius, it's about careful state management and not skipping the edge cases you'll face on the live assessment. Samsung's version probably has tight time constraints, so efficiency in implementation matters more than algorithmic complexity.
Pattern tags
You know the problem.
Make sure you actually pass it.
Faulty Keyboard recycles across companies for a reason. It's easy-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 by an Amazon engineer who used it to pass JPMorgan's OA and system design loop. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Faulty Keyboard interview FAQ
Is this really asked at Samsung?+
Yes, Samsung reports this problem in their interview cycle. With 78.6% acceptance, it's a real filter, not a gimme. The gap between your practice rate and the live version often comes from time pressure and missing the backspace edge cases.
What's the trick I'm probably missing?+
You need to track the actual output string as you simulate typing and deleting. Use a stack or string and pop when you see the backspace character. The catch is handling multiple consecutive backspaces and backspaces when there's nothing left to delete. Test those cases hard.
Is this more String or Simulation?+
Both equally. You're manipulating a string, but the real problem is simulating the keyboard behavior correctly. Neither is hard alone, but combining them cleanly under time pressure on the OA is where candidates slip.
How much harder is this than it looks?+
The 78.6% acceptance suggests it's easier than you think, but that's in controlled practice. On a live assessment with time limits and proctor anxiety, the simulation logic can trip you up if you don't pre-code the stack pattern and test backspace edge cases first.
Should I use a list or a string for the result?+
Use a list or stack if your language supports it efficiently (pop is O(1)). String concatenation can work but may be slower. For this problem scope, either works, but list/stack is cleaner and faster for repeated deletions.
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