Don't want to start a separate comment thread repeating what's been said before, but I felt compelled to contribute to the crescendo of this one instead.

These visualisations are simply great.

Programmer of 30 years here. Studied Big O formally around 20 years ago. Loved the refresher. But beyond all that, I found the in-line animation examples were just superbly executed.

I would have absolutely *loved* this style of teaching in my undergraduate algorithms class. It is tangible and practical - not to mention fun.

Kudos to the author.