TWC279

Challenge Link

Task1

We make a hash out of two arrays and sort it according to values:

#!/usr/bin/env perl
use strict;
use warnings;
use List::Util qw(zip);

sub sort_letters{
  my %h = map {$_->[0] => $_->[1]} zip $_[0],$_[1];
  join '',sort{$h{$a} <=> $h{$b}} keys %h
}

printf "%s\n",sort_letters(['R','E','P','L'],[3,2,1,4]);
printf "%s\n",sort_letters(['A','U','R','K'],[2,4,1,3]);
printf "%s\n",sort_letters(['O','H','Y','N','P','T'],[5,4,2,6,1,3]);

Task2

tr in perl returns the number of replacements in scalar context and we just check if it is even:

#!/usr/bin/env perl
use strict;
use warnings;

sub split_string{
  $_[0] =~ tr/aeiouy// % 2 == 0
}

printf "%d\n",split_string('perl');
printf "%d\n",split_string('book');
printf "%d\n",split_string('good morning');

TWC278

Challenge Link

Task1

We separate the alphas from digits in each word of the string and make a hash from it, then we sort that hash according to the values and return the result as a string:

#!/usr/bin/env perl
use strict;
use warnings;

sub sort_string{
  my %h = map{/(\w+)(\d+)/} split ' ',$_[0];
  join ' ',sort{$h{$a} <=> $h{$b}} keys %h
}

printf "%s\n",sort_string('and2 Raku3 cousins5 Perl1 are4');
printf "%s\n",
  sort_string('guest6 Python1 most4 the3 popular5 is2 language7');
printf "%s\n",sort_string('Challenge3 The1 Weekly2');

Task2

We match the desired part non-greedily, sort it, and substitute it in the given string:

#!/usr/bin/env perl
use strict;
use warnings;

sub reverse_string{
  $_[0] =~ s/(.*?$_[1])/join '',sort split '',$1/er
}

printf "%s\n",reverse_string('challenge','e');
printf "%s\n",reverse_string('programming','a');
printf "%s\n",reverse_string('champion','b');

TWC277

Challenge Link

Task1

We count the array elements in a hash and check which ones are equal to two:

#!/usr/bin/env perl
use strict;
use warnings;

sub count_common{
  my %h;
  $h{$_}++ foreach @{$_[0]},@{$_[1]};
  (grep{$_ == 2}values %h) // 0
}

printf "%d\n",
  count_common(['Perl','is','my','friend'],
	       ['Perl','and','Raku','are','friend']);
printf "%d\n",
  count_common(['Perl','and','Python','are','very','similar'],
	       ['Python','is','top','in','guest','languages']);
printf "%d\n",
  count_common(['Perl','is','imperative','Lisp','is','functional'],
	       ['Crystal','is','similar','to','Ruby']);

Task2

We count how many times the given condition is met, for each combination of pairs of elements:

#!/usr/bin/env perl
use strict;
use warnings;
use Algorithm::Combinatorics qw(combinations);
use List::AllUtils qw(min uniq);

sub strong_pairs{
  scalar grep{abs($$_[0] - $$_[1]) < min(@$_)}
    combinations([uniq @{$_[0]}],2)
}

printf "%d\n",strong_pairs([1,2,3,4,5]);
printf "%d\n",strong_pairs([5,7,1,7]);

TWC276

Challenge Link

Task1

If the sum of any of the pairs is divisible by 24, we increment the count value:

#!usr/bin/env perl
use strict;
use warnings;

sub complete_day{
  my ($arr) = @_;
  my $count = 0;
  foreach my $i(0..$#$arr-1){
    foreach my $j($i+1..$#$arr){
      $count++ if(($arr->[$i] + $arr->[$j]) % 24 == 0)
    }
  }
  $count
}

printf "%d\n",complete_day([12,12,30,24,24]);
printf "%d\n",complete_day([72,48,24,55]);
printf "%d\n",complete_day([12,18,24]);

Task2

We count the values, and sum the ones which have a weight equal to the max weight of the elements:

#!/usr/bin/env perl
use strict;
use warnings;
use List::Util qw(max sum0);

sub maximum_frequency{
  my %h;
  $h{$_}++ foreach @{$_[0]};
  my $max = max values %h;
  sum0 grep {$_ if $_ == $max} values %h
}

printf "%d\n",maximum_frequency([1,2,2,4,1,5]);
printf "%d\n",maximum_frequency([1,2,3,4,5]);

TWC273

Challenge Link

Task1

We count the character's occurrences and calculate its percentage:

#!/usr/bin/env perl
use strict;
use warnings;
use POSIX qw(round);

sub percentage_of_character{
  my ($str,$char) = @_;
  my $count =()= $str =~ /\Q$char/g;
  round(100 * $count / length $str)
}

printf "%d\n",percentage_of_character('perl','e');
printf "%d\n",percentage_of_character('java','a');
printf "%d\n",percentage_of_character('python','m');
printf "%d\n",percentage_of_character('ada','a');
printf "%d\n",percentage_of_character('ballerina','l');
printf "%d\n",percentage_of_character('analitik','k');

Task2

We see if there's no 'a' character after the last 'b' character:

#!/usr/bin/env perl
use strict;
use warnings;

sub b_after_a{
  (-1 != index($_[0],'b')) >= rindex($_[0],'a')
}

printf "%d\n",b_after_a('aabb');
printf "%d\n",b_after_a('abab');
printf "%d\n",b_after_a('aaa');
printf "%d\n",b_after_a('bbb');

TWC272

Challenge Link

Task1

Replacing each . with [.]:

#!/usr/bin/env perl
use strict;
use warnings;

sub defrag_ip_address{
  $_[0] =~ s/\./[.]/gr
}

printf "%s\n",defrag_ip_address('1.1.1.1');
printf "%s\n",defrag_ip_address('255.101.1.0');

Task2

Subtracting the absolute values of pairs and taking their sum:

#!/usr/bin/env perl
use strict;
use warnings;
use List::Util qw(sum0);
use List::MoreUtils qw(slide);

sub string_score{
  sum0 slide {abs(ord($b) - ord($a))} split '',$_[0]
}

printf "%d\n",string_score('hello');
printf "%d\n",string_score('perl');
printf "%d\n",string_score('raku');

TWC271

Challenge Link

Task1

We return the index of the array with the largest sum:

#!/usr/bin/env perl
use strict;
use warnings;
use List::Util qw(sum0);

sub maximum_ones{
  my $max = 0;
  map{my $c = sum0 @{$_[0]->[$_]}; $max = $_+1 if $c > $max} 0..$#{$_[0]};
  $max
}

printf "%d\n",maximum_ones([[0,1],[1,0]]);
printf "%d\n",maximum_ones([[0,0,0],[1,0,1]]);
printf "%d\n",maximum_ones([[0,0],[1,1],[0,0]]);

Task2

We first sort by the pop count of the items then if they were equal, by the elements themselves:

#!/usr/bin/env perl
use strict;
use warnings;
use ntheory qw(hammingweight);
use Data::Show;

sub sort_by_one_bits{
  sort{hammingweight($a) <=> hammingweight($b) || $a <=> $b} @{$_[0]}
}

print show sort_by_one_bits([0,1,2,3,4,5,6,7,8]);
print show sort_by_one_bits([1024,512,256,128,64]);