I started my competitive programming journey through the October Long Challenge back in 2019. Since then, I have felt that Codechef has provided me a great platform to learn new concepts and widely increase the span of my knowledge. The February Long Challenge 2021 was interesting to me in two respects.
Firstly, among the solvable problems per se, the hardest problem (the one with minimum accurate submissions), DRE3HGF, was hard to solve even for 10 points, requiring only square root decomposition and no fancy data structures which surprised me to a great extent.
Secondly, among the 17 challenges that I have witnessed, this was the first long challenge in which the challenge problem was completely solvable and a contestant was able to fit the solution in the given time constraints as well.
This Long challenge, I also felt that the time constraints had been specially kept tight to mostly allow only optimal solutions to fit in the given time constraints. I feel Long challenges are a great way to learn new concepts and to tackle some challenging questions. I really appreciate Codechef for providing me with this opportunity to share my experience.