Re^4: list of four digit lock combinations without repeated digits

Very interesting info, thank you. I often wonder about such efficiency when writing perl but it doesn't usually matter too much. I do write postfix loops because they're pretty and one-line friendly (I ❤ print$_ for@_) but not when they're nested because I tend to forget about them. If they're really much faster I could use comments to remind myself. Anyway your version is slightly faster (~0.750) but the data has whitespace and when using map to remove that it gets even slower than mine. What's going on?

time perl -MAlgorithm::Combinatorics=:all -wle'
my $i=variations_with_repetition(["a".."z"],$ARGV[0]); 
my @x; push @x, map {s/ //gr} qq[@$_] while $_=$i->next; 
print scalar @x' 4
[download]

real 0m1.050s

Profile:

perl -d:NYTProf -MAlgorithm::Combinatorics=:all -wle'
my $i=variations_with_repetition(["a".."z"],$ARGV[0]); 
my @x; push @x, map {s/ //gr} qq[@$_] while $_=$i->next; 
print scalar @x' 4; nytprofhtml --open
[download]

_{STOP REINVENTING WHEELS, START BUILDING SPACE ROCKETS!—CPAN} 🐫

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Re^5: list of four digit lock combinations without repeated digits by BrowserUk (Patriarch) on Jun 21, 2018 at 10:32 UTC
when using map to remove that it gets even slower than mine. What's going on? You are starting the regex engine 210 times. If you don't want the spaces, don't put them in to start with. Rather than `"@$_"` use `join'',@$_` or `pack 'A*', @$_`, or set $"=undef. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". The enemy of (IT) success is complexity. In the absence of evidence, opinion is indistinguishable from prejudice. Suck that fhit	[reply] [d/l] [select]
Re^6: list of four digit lock combinations without repeated digits by usemodperl (Beadle) on Jun 22, 2018 at 02:35 UTC
If you don't want the spaces, don't put them in to start with. Rather than "@$_" use join'',@$_ or pack 'A', @$_, or set $"=undef.* Of course I picked the slowest way(s) not to do it. I've got a bad habit of overthinking problems and overengineering solutions and shoving a regex into map like that when I know all about join is typical! Your keisaku is appreciated, I can see: map + regex: ~0m0.950s `time perl -MAlgorithm::Combinatorics=:all -wle' my $i=variations_with_repetition(["a".."z"],$ARGV[0]); my @x; push @x, map {s/ //} qq[@$_] while $_=$i->next; print scalar @x' 4` [download] map: ~0m0.830s `time perl -MAlgorithm::Combinatorics=:all -wle' my $i=variations_with_repetition(["a".."z"],$ARGV[0]); my @x; push @x, map {$_} qq[@$_] while $_=$i->next; print scalar @x' 4` [download] pack: ~0m0.820s `time perl -MAlgorithm::Combinatorics=:all -wle' my $i=variations_with_repetition(["a".."z"],$ARGV[0]); my @x; push @x, pack "A*", qq[@$_] while $_=$i->next; print scalar @x' 4` [download] join: ~0m0.720s `time perl -MAlgorithm::Combinatorics=:all -wle' my $i=variations_with_repetition(["a".."z"],$ARGV[0]); my @x; push @x, join "", @$_ while $_=$i->next; print scalar @x' 4` [download] $"=undef: ~0m0.720s `time perl -MAlgorithm::Combinatorics=:all -le' my $i=variations_with_repetition(["a".."z"],$ARGV[0]); my @x; qq[$"=undef]; push @x, qq[@$_] while $_=$i->next; print scalar @x' 4` [download] _{STOP REINVENTING WHEELS, START BUILDING SPACE ROCKETS!—CPAN} 🐫	[reply] [d/l] [select]
Re^7: list of four digit lock combinations without repeated digits by BrowserUk (Patriarch) on Jun 22, 2018 at 06:12 UTC
`push @x, pack "A", qq[@$_] while $_=$i->next;`* That would probably match if not beat join, if you weren't stringifying the array twice. Ie. Use `push @x, pack "(A)", @$_ while $_=$i->next;` Of course, if you want to put all the sequences as strings into an array, this is easier and probably quicker; `my @x = map join( '', @$_ ), variations_with_repetition( ["a".."z"], 4 + );; print scalar @x;; 456976` [download] And if all you want to do is print the count, then: `[ 7:10:21.87] C:\test>perl -MAlgorithm::Combinatorics=:all -le"print s +calar( () = variations_with_repetition( ["a".."z"], $ARGV[0] ) )" 4 456976 [ 7:10:27.12] C:\test>` [download] BTW, that is one seriously quick machine you're running. What is it? (6x faster than my (admittedly ancient) box. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". The enemy of (IT) success is complexity. In the absence of evidence, opinion is indistinguishable from prejudice. Suck that fhit	[reply] [d/l] [select]
Re^8: list of four digit lock combinations without repeated digits by usemodperl (Beadle) on Jun 22, 2018 at 23:57 UTC


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