TWC256

Challenge Link

Task1

We check each string with the reverse of all others and increment the count if they are equal:

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

sub maximum_pairs{
  my ($a) = @_;
  my $c = 0;
  map{my $i = $_;
      map{$c++ if $a->[$i] eq reverse $a->[$_]}$i+1..$#$a}0..$#$a;
  $c
}

printf "%d\n", maximum_pairs(['ab','de','ed','bc']);
printf "%d\n", maximum_pairs(['aa','ba','cd','ed']);
printf "%d\n", maximum_pairs(['uv','qp','st','vu','mn','pq']);

Task2

We keep picking a character from each string alternatively until we exhaust the strings:

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

sub merge_strings{
  my ($res,$m,$n) = ('',length $_[0],length $_[1]);
  for(my $i = 0; $i < $m || $i < $n; ++$i){
    $res .= substr $_[0],$i,1 if $i < $m;
    $res .= substr $_[1],$i,1 if $i < $n;
  }
  $res
}

printf "%s\n",merge_strings('abcd','1234');
printf "%s\n",merge_strings('abc','12345');
printf "%s\n",merge_strings('abcde','123');