TWC262

Challenge Link

Task1

We count the number of negative and positive numbers in the array and return the maximum:

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

sub max_positive_negative{
  my ($neg,$pos) = 0 x 2;
  map{$neg++ if $_ < 0;$pos++ if $_ > 0}@{$_[0]};
  max $neg,$pos
}

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

Task2

For each (i,j) pair we check if the condition (i * j mod k == 0) holds and count them:

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

sub count_equal_divisible{
  my ($arr,$k) = @_;
  my $count = 0;
  foreach my $i(0..@$arr-2){
    foreach my $j($i+1..@$arr-1){
      ++$count if $arr->[$i] == $arr->[$j] && ($i*$j) % $k == 0
    }
  }
  $count
}

printf "%d\n",count_equal_divisible([3,1,2,2,2,1,3],2);
printf "%d\n",count_equal_divisible([1,2,3],1);

TWC261

Challenge Link

Task1

We subtract the sum of each digit in each number from the sum of the numbers and take its absolute value:

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

sub element_digit_sum{
  abs(sum0(map{split ''}@{$_[0]}) - sum0(@{$_[0]}))
}

printf "%d\n",element_digit_sum([1,2,3,45]);
printf "%d\n",element_digit_sum([1,12,3]);
printf "%d\n",element_digit_sum([1,2,3,4]);
printf "%d\n",element_digit_sum([236,416,336,350]);

Task2

While $start is in the list, we keep multiplying it by 2:

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

sub multiply_by_two{
  my ($arr,$start) = @_;
  $start *= 2 while((firstidx{$start == $_}@$arr)!=-1);
  $start
}

printf "%d\n",multiply_by_two([5,3,6,1,12],3);
printf "%d\n",multiply_by_two([1,2,4,3],1);
printf "%d\n",multiply_by_two([5,6,7],2);

TWC260

Challenge Link

Task1

We count the occurrences of each integer in a hash, then check if the length of the values of that hash is equal to the length of the unique values,  if so we return 1 else 0:

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

sub unique_occurences{
  my %h;
  $h{$_}++ foreach @{$_[0]};
  my @values = values %h;
  @values == (uniq @values) || 0
}

printf "%d\n",unique_occurences([1,2,2,1,1,3]);
printf "%d\n",unique_occurences([1,2,3]);
printf "%d\n",unique_occurences([-2,0,1,-2,1,1,0,1,-2,9]);

Task2

We construct an array of all permutations of the given string, join each tuple to a string, and remove the duplicates, then sort and find the index of the string which is equal to the argument of the subroutine:

#!/usr/bin/env perl
use strict;
use warnings;
use Algorithm::Combinatorics qw(permutations);
use List::MoreUtils qw(onlyidx uniq);

sub dictionary_rank{
  1+onlyidx{$_ eq $_[0]}
    sort{$a cmp $b}
    uniq map{join'',@$_}
    permutations([split '',$_[0]])
}

printf "%d\n",dictionary_rank('CAT');
printf "%d\n",dictionary_rank('GOOGLE');
printf "%d\n",dictionary_rank('SECRET');