#!/usr/bin/perl -w
use strict;

my @source_data = (
    [ 100, 204, 312 ],
    [ 102, 313, 409 ],
    [ 205, 206, 315 ],
    [ 207, 210, 314 ],
);

my @sorted_numbers = sort map { @{$_} } @source_data;

# Using hash for the lookup. If your N numbers are fairly dense over
# 0..N then use an array for reduced mem consumption
my %from_whence;
foreach my $source_array (@source_data) {
    my $index = 0;
    foreach my $number (@$source_array) {
        $from_whence{$number} = [$source_array, $index];
        ++$index;
    }
};

# Look for 4 contig values
my @recent;
foreach my $number (@sorted_numbers) {
    push @recent, [ $number, $from_whence{$number} ];
    next unless scalar @recent > 4;
    shift @recent;
    check_and_handle_contig(\@recent);
}

exit 0;

sub check_and_handle_contig {
    my $numbers_info = shift;
    my $lastnum = undef;
    foreach my $numinfo (@$numbers_info) {
        my $num = $numinfo->[0];
        if ($lastnum) {
            return unless $num == $lastnum + 1;
        }
        $lastnum = $num;
    }

    print "Found sequence:\n";
    foreach my $numinfo (@$numbers_info) {
        my $num = $numinfo->[0];
        my $info = $numinfo->[1];
        print "$num from $info->[0]:$info->[1]\n";
    }
}

##</code><code>##

Found sequence:
204 from ARRAY(0x814bc28):1
205 from ARRAY(0x8188e94):0
206 from ARRAY(0x8188e94):1
207 from ARRAY(0x8188ed0):0
Found sequence:
312 from ARRAY(0x814bc28):2
313 from ARRAY(0x8188c30):1
314 from ARRAY(0x8188ed0):2
315 from ARRAY(0x8188e94):2