## AN INTERVIEW QUESTION AT GOOGLE

I confess that I was not on top during an interview for a job at Google. The interviewer was the manager who gave his name to one of the social networks. He was very nice guy. He asked me a question:

“What is your strategy to find your car along a very long street if you don’t remember the parking place?”

Being under interview pressure, I quickly improvised an answer like this: I double the distance every time I change direction.

The mathematically correct answer might be the linear search.

To go X blocks (cars) in one direction, then 2X in the other, then 4X forwards, 8X in the reverse direction etc… The initial X depends on the standard deviation.

Now I have time to think about the real problem, I find that the theoretically correct answer is not correct for real life. My mistake was sticking to the initial data; I did not think about the real situation. There are no infinite streets in real life.

One of the practical approaches is : choose a direction and go until the end;  if I am not lucky, then go in the other direction.

When I ask a manager about the solution he said: “I will use the key signalization to find my car.” This is “a management solution”.

Is this problem an example of the math paradox: the theoretical solution is not the same as the practical choice? There are many anecdotes about mathematicians: mathematicians are absolutely right and absolutely useless.

Here the list of 140 questions at Google: