Polish Olympiad in Informatics, POI 18/2 - problem solving

Описание: I will solve problems from POI XVIII, stage 2 (Difference, Garbage, Temperature, Tree Rotations). I will explain my thought process and give some advice for those competing themselves. You can try to solve the problems yourself first: https://szkopul.edu.pl/p/default/prob... (change the language to English in the top-right corner). The stream will be in English.

I'm going to stream on Twitch at the same time:   / errichto  .

Please ask questions in live chat.
I will be happy to answer them.
If you miss the stream, the video will be available later anyway.

git repository: https://github.com/Errichto/youtube
Facebook:   / errichto  
Twitter:   / errichto  
Competitive Programming Discord: https://discordapp.com/invite/UzaURu7
What is Competitive Programming? https://en.wikipedia.org/wiki/Competi...

I'm known as Errichto. I compete in and organize programming competitions. I'm a finalist of ACM-ICPC, Topcoder Open, Facebook Hacker Cup and Google Code Jam. I got a second place in Google Code Jam 2018. Watch me if you want to practice Competitive Programming, algorithms or you want to learn for a coding interview. I share my thought process, explain everything, and mention similar problems that I know or techniques/algorithms that could be used too. Learn from me and grow your rating on Codeforces!