On simple explanations

Asymptotic complexities

Finding a pen in a classroom of n students

  • O(n^2) – Asking each student and ask him about others too
  • O(n) – Asking each student
  • O(logn) – Dividing class equally and asking each half
  • O(1) – Damn it, I have it in my pocket Person facepalming

On past, present selfand future self

Be forgiving with your past self.
Be strict with your present self.
Be flexible with your future self