Author: David Romano

Specification

P12 (**) Decode a run-length encoded list.
    Given a run-length code list generated as specified in problem P11.
    Construct its uncompressed version.

Example

> say prob12(([<4 a>],'b',[<2 c>],[<2 a>], 'd', [<4 e>]));
a a a a b c c a a d e e e e

Source code: P12-unobe.pl

use v6;

my @l = ([('4', 'a')],'b',[('2', 'c')],[('2','a')], 'd', [('4','e')]);
sub prob12 (@in) {
    my @out;
    for 0 ... (@in.end) -> $x {
        if @in[$x] ~~ Array {
            loop (my $i=0; $i < @in[$x][0]; $i++) {
                push @out, @in[$x][1];
            };
        }
        else {
            push @out, @in[$x];
        }
    }
    return @out;
}

say @l.perl;
say prob12(@l).perl;