TWC300

Challenge Link

Task1

We check the given condition for permutations of the sequence:

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

sub beautiful_arrangement{
  my $it = permutations([1..$_[0]]);
  my $c = 0;
 perm:
  while(my $p = $it->next){
    foreach my $i(1..$_[0]){
      next perm if $p->[$i-1] % $i && $i % $p->[$i-1]
    }
    $c++
  }
  $c
}

printf "%d\n",beautiful_arrangement(2);
printf "%d\n",beautiful_arrangement(1);
printf "%d\n",beautiful_arrangement(10);

Task2

We check for the given condition and find out the maximum:

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

sub nested_array{
  my ($arr) = @_;
  my $max = 0;
  foreach my $i(0..$#$arr){
    my $len = 0;
    my $set = $arr->[$i];
    my %used;
    while(!exists $used{$set}){
      undef $used{$set};
      $set = $arr->[$set];
      ++$len
    }
    $max = $len if $len > $max
  }
  $max
}

printf "%d\n",nested_array([5,4,0,3,1,6,2]);
printf "%d\n",nested_array([0,1,2]);