Mergesort - Is Bottom-Up faster than Top-Down?

Question

I\'ve been reading \"Algorithms, 4th Ed\" by Sedgewick & Wayne, and along the way I\'ve been implementing the algorithms discussed in JavaScript.

I recently took the

Answer 1

If by faster you mean fewer "iterations" then yes. If you're wondering about execution time maybe.

The reason is some of those 21,513 iterations are doing more than the 22,527 iterations.

From looking at the source it seems like some of the leaf nodes in your diagram are being sorted together not individually resulting in fewer merges and sorts but them taking longer.