TWC390

Challenge Link

Task1

We repeat each given character n times according to the given rules:

#!/usr/bin/env perl
use strict;
use warnings;
use Test::More tests => 5;

sub decode_string{
  my (@s1,@s2);
  my $num = 0;
  my $res = '';
  foreach my $c(split '',$_[0]){
    if($c =~ /\d/) {
      $num = $num * 10 + $c - '0'
    } elsif($c eq '[') {
      push @s1,$num;
      push @s2,$res;
      $num = 0;
      $res = ''
    } elsif($c eq ']') {
      my $t = '';
      for(my ($i,$n) = (0,pop @s1); $i < $n; ++$i) {
	$t .= $res
      }
      $res = (pop @s2) . $t
    } else {
      $res .= $c
    }
  }
  $res
}

is decode_string('2[3[a]]'),'aaaaaa','Example 1';
is decode_string('10[a]'),'aaaaaaaaaa','Example 2';
is decode_string('a2[b]c3[d]e'),'abbcddde','Example 3';
is decode_string('2[a2[b]c]'),'abbcabbc','Example 4';
is decode_string('1[a]2[b3[c]]'),'abcccbccc','Example 5';

done_testing();

Task2

We reorder characters until we find the smallest string:

#!/usr/bin/env perl
use strict;
use warnings;
use Test::More tests => 7;

sub order_characters{
  my ($s,$k) = @_;
  if ($k == 1) {
    my $n = length($s);
    my $doubled = $s . $s;
    my $best = substr($doubled,0,$n);
    foreach my $i(1..$n-1) {
      my $candidate = substr($doubled,$i,$n);
      $best = $candidate if $candidate lt $best
    }
    return $best
  } else {
    return join('',sort split '',$s)
  }
}

is order_characters('dbca',1),'adbc','Example 1';
is order_characters('geeks',2),'eegks','Example 2';
is order_characters('cbaed',3),'abcde','Example 3';
is order_characters('fedcba',4),'abcdef','Example 4';
is order_characters('perl',1),'erlp','Example 5';
is order_characters('oloolooo',1),'looloooo','Example 6';
is order_characters('oloooolo',1),'looloooo','Example 7';

done_testing();