timing puzzle

[Robin Becker]

Neil Cerutti wrote:
.......


  see why.
> 
> You are no longer making m copies of active_nodes.

my profiling indicated that the main problem was the removes.

> 
........
> 
> When you have to make many deletions from the middle of a
> sequence, you would normally choose a linked list. Python doesn't
> provide much support for linked lists, unfortunately.
> 
> Instead, filter your list. It looks like you can't use filter
> directly, so just do it manually.
> 
>    for i in xrange(m):
>        .......
>        saved_nodes = []
>        for A in active_nodes[:]:
>           ......
>           if not cond:
>               saved_nodes.append(A)
> 
>           ......
>        active_nodes = saved_nodes
>        .....
> 

I like this approach, better than mine.
-- 
Robin Becker