Dell Interview Question: The "Three Light Switches" ri... | Glassdoor

Interview Question

Software Developer Interview Round Rock, TX

The "Three Light Switches" riddle, which one can answer

  (and I could fortunately) on the spot one thinking through but it was a bit unexpected but a good way of testing problem solving in my opinion.

Interview Answer

1 Answer


Let consider the switches: Switch A, B, and C.

1. Turn on the switch A for about 5 minutes.
2. Turn off switch A, and turn on switch B then open the door.

If the bulb is "ON" it is switch B. Else if the bulb in "OFF" but it's hot, it is switch A. Otherwise, it is switch C.

biggied88 on Jan 23, 2016

Add Answers or Comments

To comment on this, Sign In or Sign Up.