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#!/usr/bin/env perl
#
# Create a script which takes a list of numbers from command line and print the
# same in the compact form. For example, if you pass “1,2,3,4,9,10,14,15,16”
# then it should print the compact form like “1-4,9,10,14-16”
################################################################################
use strict;
use warnings;
sub compact {
my @ns = split(/,/, shift);
my $from = my $to = shift @ns; # The first interval is the first number
my @intervals;
# Store the current interval ($from, $to) and advance to the next one
my $save = sub {
push(@intervals, $from == $to ? $from : "$from-$to");
$from = $to = shift;
};
# Iterate over the numbers, expanding the last interval or starting a new one
foreach my $n (@ns) {
if ($to == $n-1) {
$to = $n;
} else {
&$save($n);
}
}
# Store the last interval (except for empty input)
&$save if defined $to;
return join(",", @intervals);
}
foreach (@ARGV) {
print compact($_), "\n";
}
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