.

If n is the number of pieces, yes as i was talking about like two nested for loops, it is either O(n) or O(n * m) where n, m is height and length.

I also don't believe any solutions are O(n^2) if n is the number of pieces. By doing a simple nested loop with for p in pieces: twice, it times out.

Your solution is much easier to understand! Months later, this is true for me, even though I wrote my code...

first things first: what is n exactly?

@tony:

here, n being the number of pieces, the best solution is O(n) (for the precise reasons Ryanman is explaning)

I think O(n^2) is the lowest possible time as you need to have a nested loop. Take your solution for example, it has a nested loop, so its O(n^2).