The exact moment when I understood what programming actually was.

I was getting hard times at my 3rd college grade, trying to implement the recursive sudoku solver in python. Teacher spent a lot of time trying to explain me things like referential transparency, recursion and returning the new value instead of modifying the old one and everything related. I just couldn't get it.

I was one of the least productive students, i couldn't even understand merge sort.

I was struggling with for loops and indexes, and then suddenly something clicked in my head, like someone flipped a switch, and i understood everything i was explained, all at once. It was like enlightenment, like pure magic.

I had sudoku solver implemented by the end of the lecture. Linked list, hash map, sets, social graphs, i got all of these implemented later, it wasn't a problem anymore. I later got an A for my diploma.

Thank you @dementiy, you were the reason for my career to blast off.