A horse race
Recently, I had a technical interview with a startup for a back end developer position. The questions they asked was quite hard for me to answer. I don’t know if it was because I haven’t done anything for a while or I was nervous or I was just unprepared.
The interview lasted for 2 hours. It was almost disastrous. The first thing they asked was for me to fix my SQL response I sent them beforehand. It was to find duplicates and I assumed there will only be up to 2 duplicates for each record and they wanted it to be able to find more. I tried my best but I just couldn’t do it, probably because I was never doing pure SQL. I felt really bad.
Then I had to do bunch of other things. I remembered they asked me find the first n digits of pi. Then they asked me to print the index of n in pi. I took the easy path and assume n is a digit and now that I think about it, n should be a number and my solution wouldn’t be able to solve it if it is indeed a number instead of a digit because my solution was to convert pi up to 20 decimal point to string then find the index of n.
Finally, I had to write some Ruby classes to solve a simple horse racing problem. I had 2 problems at that moment. First problem, I never wrote a pure Ruby code! Second problem, I don’t have enough time to think of the solution… The problem was quite simple. Given h number of horses and t number of tracks, find the least number of races to find the first and second fastest horses. I couldn’t solve that.
This problem stuck in my head for a while. Sure, I had my chance and solving it now wouldn’t magically pass me the interview but it should calm me down. So, I think what I could do was to:
- race the horses in groups of
t - race all the first horses in groups of
t - repeat until there’s less than or
thorses - for the first 2 horses of the final group, get the second horse from their initial groups
- race the four horses to find the first and second fastest horses
- record all the races to find out how many races actually done
There you have your horses. I feel a bit redeemed.