Slitherlink or loopy puzzles...

I have seen slitherlink puzzles, or loop the loop, quite a few times in the past but they have never really appealled to me.

However I have started doing some of the easier ones recently and to my surprise after getting confused with the first few puzzles I am actually starting to quite enjoy them.

As you go through you start to spot patterns that aren't immediately obvious but once you think about them you start to realise there are only certain ways of marking cells when those patterns occur, for instance when there are two 2's diagonally then whilst you might not think that is helpful it actually is! And when there are two 3's adjacent to each other you can mark three lines immediately as far as I can tell.

It would be interesting to hear what other people think of slitherlink and any useful patterns that you can use when solving them.

The other thing I would like to know is if the puzzles ever require you to basically guess, or is there always a way to work out in a puzzle how the loop must go if you have made all the possible deductions up to the stage you are stuck up? With some puzzles I think the only way is to make a guess and then see if it works or not, but that doesn't seem that satisfying so I wondered if that is the case or not!

Re : Slitherlink or loopy puzzles

Hi Martha

There are lots of interesting solving patterns that you can use with slitherlink, and particularly there are some that work in the corners.

As you say, where you diagonally adjacent twos then there are only a couple of combinations and with adjacent threes likewise you can mark three sides straight away.

Another interesting piece of logic to look out for is when you have two 3's that are diagonally adjacent in the same way as the twos: take a look at that combination in a puzzle and see what you can find!

The most obvious ones, of course, are where you have a '0' next to a '3' as instantly you can mark in all three sides of the 3. Often when you have a 0 next to a '2' in a position where the 2 is not completely open you can also mark in the sides of the two, because of the entry/exit rule.

By that I mean the most intuitive rule but also one of the most useful that it is incredibly easy to forget: you must be able to get in AND out from a position, so for instance if placing one side of the two would lead to an area you can't progress from, then that side can't be marked. This can often be used to place a 2 next to a 0 straight away, depending on the situation of the game.

The fun thing with slitherlink is lots of little patterns reveal themselves the more puzzles you solve.

Re : Slitherlink or loopy puzzles

Hi Stacey

Thanks for the reply. Yes I agree with you about the fun thing being working out little patterns that you can use.

These are greatly time saving I am finding as with each other puzzle there are places where I no longer have to work through the possible options in my head but I just know what they are from past experience.

This makes solving a puzzle a lot quicker as I have to pause less and also often can see some telltale patterns that reduce the options down.

One thing that was obvious but I hadn't done before was with regard to a 1, where I knew that on thinking about it the path from an adjacent cell had to go down one of two sides. This meant, but I hadn't done it until now, that I could of course mark off with 'x's the other two sides of the one as it had to be one of the other two.

It is simple little things like that which nevertheless aren't obvious the first time you solve a puzzle (or at least weren't to me) that have made this puzzle type interesting so far. I don't feel ready to tackle really hard ones, and if you ever have to look too far ahead at what the loop could do I may never be ready, but for the meantime the ones I'm doing are quite challenging and enjoyable enough.

Re : Slitherlink or loopy puzzles

Anyone who has an interest in slitherlink might like to know that we've added some solving tips for slitherlink today:

http://www.puzzle-magazine.com/slitherlink-strategy-tips.php

We now have a pretty decent number of strategy guides aimed at those coming to a puzzle type for the first time