"...and while loops don't seem to work either. If i put a number for example x < 900 then the script is executed perfectly but if i leave something like x < links then it doesn't..."

while loop should work, the issue is the condition you give to the while loop (whether you take any sanp shot):

• x < 900, a predetermined big number, that probably works MOST of the time, as long as the number is big enough (so that it is greater than the eventual size of the array). But that's not how you write nice and decent code. as you want your code work ALL the time.
• x <= $#links does not work as the array is growing, but the snap shot of the array size was only taken once.
• while works if you give the correct condition such as below, in which there is no snap shot taken: (the following example simulates your situation by saying that each even number has a link that is its half.)

  use strict;
  use warnings;
  
  my @array = (1 .. 4);
  while (@array) {
      my $first = shift @array;
      print "[$first]";
      push @array, $first / 2 if (!($first % 2));
  }
  [download]

  This prints the correct answer:

  [1][2][3][4][1][2][1]
  [download]

• A for loop works as well, as long as you don't take any snap shot:

  use strict;
  use warnings;
  
  my @array = (1 .. 4);
  for my $element (@array) {
      print "[$element]";
      push @array, $element / 2 if (!($element % 2));
  }
  [download]

  This also gives the correct answer.