I have really been wanting to do a tutorials of the latest contests on CodeForces.com but really haven’t had the time to do write ups like I would like.  So I had the idea to just record everything and upload it to YouTube.  So I broke the video into three parts, one section for each problem I was able to solve.

So I hope you enjoy!

Problem A – Vanya and Fence

This was a very easy problem.   I spend a few moments showing off CodeForces in the video as well.

Problem B – Vanya and Food Processor

This video went on way to long.  This was the problem I was able to create a hack that allowed me to get an bonus 500 points from hacking.  Which is awesome.  The only thing was I changed the long to an int half way through the contest.   Which cost me a resubmission later on and over 300 points.  Very frustrated about that.

Take a look how I would solve this problem now!

Problem C – Vanya and Label

This was the last problem I was able to solve.   I had a block and knew it was a combination problem.   However, I couldn’t figure out how to do it.   I knew there may be a math formula, which was covered in the official tutorial, but I used a frequency array.  But I thought it would take to long, so I created program that generated the values for me, and I copied and pasted it into my program.

That was great, but after thinking about it I could have just pre-computed it and stored things in an array.   That is how I show you how to do it here:

Well, that is it!  Hopefully I will do more of these.  If you found this helpful, please message me on C4Cheats, or leave a comment on one of the videos!

Thank for watching!

Kyle!