Other than this, just do the same as before, except reduce monster hp (and erase when it hits 0 or less) on hit, and reduce yours if they touch you. Super easy, which kinda makes me weirded out when I see complex code for hit detection. This was really simple.
That's because the complex code is for a complex ABS. This one requires you to A.) Be right next to and facing the enemy B.) Rely entirely on a 1-tile range melee weapon.
In a more complex ABS, you would need to determine the player's X and Y coordinates, as well as the enemy X/Y coordinates, and take into account the range of the weapon. If the player is in range of the enemy(range based on what weapon they have equipped, or what ability is being used, or a number of different things), then the attack commences and you go to the hit/damage portion of the code where all those fun calculations come into play.
Using a system that takes the player and enemy x/y positions into account also allows for a larger variety of weapons and attacks. For example, a spear, staff or longsword swung in a wide arc to hit multiple enemies, or otherwise bothersome ones. Or Link's famous whirlwind spin attack.
Being bluntly honest, this -will- make a rather dull ABS, but I realize it's not meant to be complex. I will say, though, that this tutorial allows you to do basic hit detection, with the opportunity to make a rich damage algorithm, and will work well for beginners trying to get their feet wet in the event programming river. It all depends on what you want your system to do.
Though I'd imagine the combat would look something like YS Book 1 & 2