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We actually discussed this while altering the genre. The original idea I had found only used the black arrows. We decided that white arrows not indicating directionality, would lead to nicer puzzles. I think a third type of arrow might make it too confusing.

Here's the walkthrough. It's not my best genre, and found writing it out a bit messy butI think it should be clear.

Walkthrough (in white as to not spoil)

Start

R710C910 have to belong to the 10 in R8C9.
R9C7 has to belong with the 5 below it. The only other valid option could be the 7 in R9C3, except then the bottom row wouldn't work.
R10C4 has to go with the 7 in R9C3.
R8C1 has to go with the 5 above it.
R3C1 has to go with the 7 in R3C2.
R910C2 have to go with the 7 in R9C3.
R10C6 now has to go with the 5 in R10C7.
Now th only valid rectangle with that 5 is R910C57. The 10 has to be R710C810.

The 7 in R7C4 has to use R6C4 as all valid rectangles from this one all use this square.
R7C6 has to use R7C5 as all rectangles that use this square also use R7C5.
Now R6C5 can only be used by the 7 in R7C4, which makes this rectangle R57C46.

The 6 in R5C3 has to use R67C3 as all valid rectangles use these squares.
The 5 in R7C1 now can't reach any lakes, so it has to be a vertical 1 wide rectangle and always uses R6C1.
R567C2 now can only be used by the 6 in R5C3, which makes this rectangle R58C23.

The rest is just filler work. Start with the 7 in R9C3.

End

Hope this was clear and that it helped. Think it is all logically sound.

I'll have a look at a walkthrough. I did it logically for verification.

Hi

When I checked this topic there was nothing in it. so you might have still been editing it at that point. Never checked back to it till now.

I liked this idea, but haven't done many of them recently. When I just got into this type I made a bunch and started to play around with empty holes in the ceiling/floor and mismatched ceilings/floors.

As to designing them, I started by just drawing some random bookcases and seeing how they solved and pick up where some of the uniqueness pitfalls lie as they weren't generally unique.
As to building a puzzle, it's easiest to start from the sides. As those chains and posts are instantly fixed. And if the posts or chains don't make it to a certain row you can eliminate places where shelves can go.
Another easily creatable opening is if the chains and posts add up to (n-1), where n is the height, as then the chains all hang from the top and the post all stand on the ground.
When you have a chain hang somewhere in the middle it decreases the amount of shelves that can go somewhere.
Once you have build openings this way, you can start looking where there are invalid loops: when a shelve is supported by a shelve it supports. This can eliminate places where chains and posts can go. If you find such places you should try using those columns for posts and chains.

I'm not sure if it's all clear. I think it's mostly trying to get a feel for it by trying and seeing how what you put in there affects the puzzle. That's why I just started by drawing them and solving to see how it worked out and then just give it a go. Start with a few smaller and easier ones to get a feel for it.

I'll take http://puzzlepicnic.com/puzzle?1792 as an example.

I opted to make a puzzle with all rows to have 4 shelves for this one.
First I fixed the two sides to 1/2 and 1/2. Because all chains and post have to be functional you have shelves on the left and right side in row 1 and row 3. This also made 2 shelve spaces in row 2 to be unreachable so the rest of the second row is shelves.
Now I chose for column 2 to only have one chain and no posts. This means it had to support the shelve in row 2 and nothing else. This chain has to be supported by the shelve in row 1. So this has to extend at least one more to the right. Also the shelve on the left in row 3 has to extend one to the right.
Then in column 5 I placed 0 chains and in column 1 chain. This makes it impossible for the shelve in row 2 to hang from the shelve in row 1. As you can't support the shelve in row 1, if the only chain in column 6 is hanging from it. This means the shelve in row 2 is supported by a post.
Next I chose for column 6 to also have 1 post. This means the shelve in row 3 can't be support in column 6 so must extend to the left. This fills row 3 with 4 shelve spaces and leave the rest of the row empty.
The right shelve in row 3 has to be supported with a post in column 5 as it supports the shelve in row 2 and thus can't hang from it. With that post in place, I made column 5 to only have one post. Thus the post has to be supported by shelves in row 4, which extend one to the left.and 2 to the right.
With the current information most of the puzzle fills itself out. Just have to fix column 3, which coul be 0/2 or 1/1 for a unique and valid puzzle. I figured 1/1 was the nicest option.

I hope this is clear and it helps a bit with how to build these puzzles.

The loop can only turn in the direction of an arrow, so no.

Thanks. I had been trying to get it as far as possible. A few earlier attempts had some overlapping areas. Took a while to get it right.

Could you show me the answer to the turning snake? I've looked at it a few times now and I keep running into the same logic dead end I ran into during the competition.

As you can see, the puzzle is almost completely rotationally symmetric, except for one pair of clues. You can see how much effect these 2 different clues have on the total solution.

Number: Puzzle #2518
Genre: Fences
Author: Bram
Appeared at: March 20, 2011