Beefy Boxes and Bandwidth Generously Provided by pair Networks
P is for Practical
 
PerlMonks  

Re^2: Analysing a (binary) string.

by hdb (Prior)
on Jun 28, 2013 at 12:23 UTC ( #1041239=note: print w/ replies, xml ) Need Help??


in reply to Re: Analysing a (binary) string.
in thread Analysing a (binary) string. (Solved)

I cannot see where you get N factorial from. To me it seems what you describe is N^2. This is also what I get from the brute force method below:

use strict; use warnings; use Time::HiRes qw/time/; sub find_best_offset { my $strref = shift; my $n = length $$strref; my $mindiff = $n; my $best_offset = -1; for( my $i=1; $i<=$n/2; $i++ ) { # shift/rotate string and compare to original my $diff = $$strref ^ substr( $$strref, -$i ).substr( $$strref +, 0, -$i ); # number of differing characters between shifted string and or +iginal my $ndiff = $diff =~ tr/\0//c; # test for and keep optimal solution if( $ndiff < $mindiff ) { return $i unless $ndiff; # best case! $mindiff = $ndiff; $best_offset = $i; } } return $best_offset; } for ( 9, 99, 999, 9999, 99999 ) { my $t = time; my $str1 = "01234567890123456789".("01234567890123456x89" x $_); print find_best_offset( \$str1 ); print "\t$_\t",time-$t,"\n"; }


Comment on Re^2: Analysing a (binary) string.
Download Code

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://1041239]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others about the Monastery: (6)
As of 2015-07-30 02:30 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    The top three priorities of my open tasks are (in descending order of likelihood to be worked on) ...









    Results (269 votes), past polls