A decade or so ago, after an interview that didn't go that well, a candidate reached out asking for feedback. I gave him some algorithms and data structures advice and where to read what and stuff like that and he responded really positively then reached out to me months later to tell me he went and learned all the stuff and got a job at some now-famous startup (Airbnb? I don't remember). I was early in my career back then and was happy for him. Now, if I were to do that I'd be like "Damn, this guy is capable of taking the feedback and actioning on it. I should have somehow found a way to hire him!"

Haha, I hope he's doing well wherever he is :)