On Fri, Sep 11, 2015 at 8:10 PM, John Cowan <xxxxxx@mercury.ccil.org> wrote:

> It's O(1) vs. O(N), which quickly matters, especially when it's executed in
> a loop.

I don't understand this.

I'm presuming that constructing the list of keys take O(N) time, whereas one can find a single element to remove in O(1).