demoralizer and I were discussing our 2+ years old code and I thought it'd be a good motivation for newbies and pupil who write cancer currently.
Please contibute by sharing code(in spoiler tag) or links to your of your big brain moments from back when you were low rated.
My biggest big brain moment was when I assumed inbuilt std::sort must be slower, so copied merge sort from gfg. https://www.codechef.com/viewsolution/23270721