This was simply a challenge put out by a friend.

I tried to make this work in a couple of the languages I use most often (T-SQL, COBOL, and C#) but I was using a looping method that just was not very efficient. I tried to write something in PERL because I've used it to split files and for very minor file manipulation but again my approach was looping based. One of my friends suggested using a hash but my implementation of the hash was to find results using grep and then loop through.

Finally I realized that I couldn't come up with an appropriate solution and sought the wisdom of the experts and it has been a tremendous learning experience.

As for the use, this was simply an exercise to get the correct answer with the most efficient code. I was able to get the correct answer but my runtimes were longer than a day. One of my friends said he solved it with hashing and his program ran in 5 minutes.

I had the answer but wanted to see what the most efficient way of solving this problem.

Thank you for your participation!