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#!/usr/local/bin/perl
use strict;
use warnings;
use feature qw(say);
use Test::More;
use Benchmark qw(cmpthese);
my $nspace = join '', 1..1000;
my $ncomma = join ',',1..1000;
my $lint_x = my $lint = ('9' x 999).'8';
my $lint_y = ++$lint_x;
$lint_y++;
my @tests = (
[ 1234, '1,2,3,4' ],
[ 91011, '9,10,11' ],
[ 10203, '10203' ],
## Numerical comparisons don't work....
[ $nspace, $ncomma ], ## 2895 digit no -> 1..1000
## Have to store range as can't use range operator here...
[ $lint.$lint_x.$lint_y, $lint.','.$lint_x.','.$lint_y ], ## 3001 digit no -> 2 x 1000 digit + 1001 digit no.
[ $lint.$lint_x, $lint.','.$lint_x ], ## 2000 digit no -> 2 x 1000 digit
[ $lint_x.$lint_y, $lint_x.','.$lint_y ], ## 2001 digit no -> 1000 digit + 1001 digit no.
[ $nspace.'99', $nspace.'99' ], ## 2895 digit no -> 2895 digit no
);
is( join(',',@{splitnum($_->[0])}),$_->[1] ) foreach @tests;
is( join(',',@{splitnum_optimized($_->[0])}),$_->[1] ) foreach @tests;
done_testing();
cmpthese( 120, {
a => sub { splitnum($_->[0]) foreach @tests; },
c => sub { splitnum_optimized($_->[0]) foreach @tests; },
});
sub splitnum {
my( $in, $start ) = ( shift, '' );
for( split //, substr $in, 0, (my $len = length $in) >> 1) {
## $start contains the first number of sequence
## each time through the loop we will add the
## next digit eg 1, 12, 123
##
## $end contains a copy of this, which we will
## then incremement as we generate the sum
my @range = ( my $str = my $end = $start .= $_ );
## We concatenate the of "end" onto $string until
## it is equal to or larger than the input number
($str .= ++$end) && push @range, $end while $len > length $str;
## Finally we return the list if the input and
## string are the same. Note we will always get
## a true value as in the last loop
## $in == $start == $end == $string
return \@range if $str eq $in;
}
return [$in];
}
## We work in string space - as this works best for large values of input
## like the 123....9991000 example above..
##
## There are some optimizations you could try {e.g. looping up to half the
## length of $n - but only really valid if you are getting very large
## values of $n...}
## We can add some optimization here... check that we match the string
## otherwise return;
sub splitnum_optimized {
my( $in, $start ) = ( shift, '' );
for( split //, substr $in, 0, (my $len = length $in) >> 1) {
my @range = ( my $str = my $end = $start .= $_ );
($str .= ++$end) && push @range,$end while ($len > length $str) &&
$end eq substr $in,length($str)-length($end),length($end);
return \@range if $str eq $in;
}
return [$in];
}
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