1.raku

my $ct = 0;
my $prev;

for "input.txt".IO.lines -> $num {
  $ct++ if defined($prev) && $num > $prev;
  $prev = $num;
}

say $ct;

2.raku

my $ct = 0;
my $prev;
my @window = ();

for "input.txt".IO.lines -> $num {
  @window.push($num);
  next if @window.elems < 3;
  @window.shift while @window.elems > 3;
  my $sum = [+] @window;
  $ct++ if defined($prev) && $sum > $prev;
  $prev = $sum;
}

say $ct;

2b.raku

my $ct = 0;
my $prev;
                
for "input.txt".IO.lines.rotor(3 => -2) -> @window {
  my $sum = [+] @window;
  $ct++ if defined($prev) && $sum > $prev;
  $prev = $sum;                         
}                                        
say $ct;

2c.raku

say "input.txt".IO.lines
  .rotor(3 => -2)
  .map(*.sum)
  .rotor(2 => -1)
  .grep({ $_[1] > $_[0] })
  .elems;

2d.raku

say "input.txt".IO.lines
  .rotor(3 => -2)
  .map(*.sum)
  .rotor(2 => -1)
  .flat
  .grep(&[<])
  .elems;