How to prepare for codechef long and short contest?
Participate!! And make sure that you are solving unsolved problems after the contest!!
First of all you should participate in each long and short contest this will help you to understand that how much time and skills you need to solve problems in these contest besides that you should practice previous long and short challenges questions but keep in mind that nobody solves all 10 and all 5 questions in their first attempt so you should practice by making a plan of solving in a order like you can solve first 3 question of previous long and short challenges in one week then increase it to 5 and so on this will help you to improve you programming skills without creating any extra pressure on you