Beefy Boxes and Bandwidth Generously Provided by pair Networks
The stupid question is the question not asked

RE: RE: Generating a Pattern

by eak (Monk)
on Aug 06, 2000 at 07:58 UTC ( #26402=note: print w/replies, xml ) Need Help??

in reply to RE: Generating a Pattern
in thread Generating a Pattern

I first have to say that I really enjoyed this problem. It took me a little while to come up with a working algorithm, unfortunately it wasn't at elegant as yours. I thought I would play with your version to see if I could improve upon it a bit. The only thing I could do was add the use of references which reduces the memcopy time on larger lists. Below is a script that benchmarked the old 'non_ref' vs. the new 'ref'. Not necessarily staggering, but an improvement. I compacted the for loop for flipping it around and putting the for statement at the end of the conditional line.
#!/usr/bin/perl use Benchmark; my $count = 100; my $end = 30; sub ref { my $a = [1]; for(1..$end){ # print "@$a\n"; my @na; ($na[-1] == $_ ? $na[-2]++ : push @na, (1, $_)) for @$a; $a = \@na; } } sub no_ref { my @a = (1); my @na; for (1..$end){ # print "@a\n"; @na = (); ($na[-1] == $_ ? $na[-2]++ : push @na, (1, $_)) for @a; @a = @na; } } timethese($count, { 'no_ref' => \&no_ref , 'ref' => \&ref} ); + +
Benchmark: timing 100 iterations of no_ref, ref...
    no_ref: 11 wallclock secs (11.12 usr +  0.04 sys = 11.16 CPU)
       ref:  9 wallclock secs ( 8.34 usr +  0.06 sys =  8.40 CPU)  

Log In?

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://26402]
and all is quiet...

How do I use this? | Other CB clients
Other Users?
Others exploiting the Monastery: (4)
As of 2017-01-23 03:24 GMT
Find Nodes?
    Voting Booth?
    Do you watch meteor showers?

    Results (190 votes). Check out past polls.