PWC091 - Jump Game


On with TASK #2 from the Perl Weekly Challenge #091. Enjoy!

The challenge

You are given an array of positive numbers @N, where value at each index determines how far you are allowed to jump further. Write a script to decide if you can jump to the last index. Print 1 if you are able to reach the last index otherwise 0.

The questions

The challenge is pretty clear, apart from a detail… is @N really composed of positive numbers only? That 0 in the second example looks a bit out of place 🧐

The solution

Here we go:

sub jump_game ($N) {
   my $position = 0;
   $position += $N->[$position] while $position < $#$N && $N->[$position];
   return $position == $#$N ? 1 : 0;

Here, it’s really just a matter of following the crumbs. We start with our $position tracker at index 0, then advance it according to the contents of the array, taking a few cares:

  • if the index goes exactly on the last spot or beyond, it’s time to stop;
  • if the jump length is 0 we stop as well… and avoid an infinite loop!

After the loop terminates, it’s a matter of figuring if we landed to the last position or not.

Have a good one!

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