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]);

TWC269

Challenge Link

Task1

We count the number of even numbers because an even number's right most bit is 0, and see if that count is greater than one:

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

sub bitwise_or{
  (grep{($_ & 1) == 0} @{$_[0]}) > 1
}

printf "%d\n",bitwise_or([1,2,3,4,5]);
printf "%d\n",bitwise_or([2,3,8,16]);
printf "%d\n",bitwise_or([1,2,5,7,9]);

Task2

We keep pushing elements into two arrays as the requirements and concatenate and return the results:

#!/usr/bin/env perl
use strict;
use warnings;
use Data::Show;

sub distribute_elements{
  my @ret1 = shift @{$_[0]};
  my @ret2 = shift @{$_[0]};
  while(@{$_[0]}){
    my $e = shift @{$_[0]};
    $ret1[-1] > $ret2[-1] ? push @ret1,$e : push @ret2,$e;
  }
  @ret1,@ret2
}

print show distribute_elements([2,1,3,4,5]);
print show distribute_elements([3,2,4]);
print show distribute_elements([5,4,3,8]);

TWC268

Challenge Link

Task1

We take the absolute value of the first elements of arrays after sorting them:

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

sub magic_number{
  my @x = sort{$a <=> $b} @{$_[0]};
  my @y = sort{$a <=> $b} @{$_[1]};
  abs($x[0] - $y[0])
}

printf "%d\n",magic_number([3,7,5],[9,5,7]);
printf "%d\n",magic_number([1,2,1],[5,4,4]);
printf "%d\n",magic_number([2],[5]);

Task2

After sorting the array, we keep removing pairs of elements and push its reverse to the array that we want to return:

#!/usr/bin/env perl
use strict;
use warnings;
use Data::Show;

sub number_game{
  my @arr = sort{$a <=> $b} @{$_[0]};
  my @ret;
  push @ret,reverse splice @arr,0,2 while(@arr);
  @ret
}

print show number_game([2,5,3,4]);
print show number_game([9,4,1,3,6,4,6,1]);
print show number_game([1,2,2,3]);