#!/usr/bin/perl
use strict;
use warnings;
use v5.10;

# PWC 131 task 2 - Peter Campbell Smith - 2021-09-20

# You are given a string of delimiter pairs and a string to search.

# Write a script to return two strings, the first with any characters matching
# the “opening character” set, the second with any matching the “closing character” set.

my $input;

# loop over input examples
until (eof(DATA)) {
    $input = <DATA>;
    chop $input;
    do_task();
}

sub do_task {

    my ($prev, $output);

    # loop over list
    $prev = -1;
    while ($input =~ m|(\d+)|g) {          # consecutive  # non-consecutive
    	$output .= ($1 == ($prev + 1)) ?   ", $1" :       "], [$1";
    	$prev = $1;
    }
    $output =~ s|...|(|;   # tidy the start of $output
    say "\nInput:  ($input)\nOutput: $output])";
}

__DATA__
1, 2, 3, 6, 7, 8, 9
11, 12, 14, 17, 18, 19
2, 4, 6, 8
1, 2, 3, 4, 5