Hashiwokakero (or Hashi for short) is a Japanese puzzle. I discovered it in the back of a magazine at my haircutter, of all places. Like sudoku, it's an abstract puzzle requiring reasoning about a number of constraints at once.

A Hashi puzzle

The numbered circles are islands, your task is to fill in the bridges connecting them. There can be zero, one or two bridges between each pair of islands, orthogonally. Bridges cannot cross, and the number on the island indicates the number of bridges to the island. Lastly, all the islands must be connected:

The solution

Indigo Puzzles has the nicest online implementation: not only can you interactively solve the puzzle, but you can ask for advice, and it will patiently explain a possible next deduction, and why. They have lots of puzzles if you join the site (free).

BTW: Hashi is one of the puzzles published by Nikoli, a Japanese puzzle magazine with many types of puzzles.

tagged: » 4 reactions

Comments

[gravatar]
Stuart Langridge 10:30 AM on 23 Dec 2007

This is also included in Simon Tatham's portable puzzle collection, along with loads of others.

[gravatar]
Wild Bill 7:34 PM on 23 Dec 2007

Yikes. Just when I was kicking my suduko habit. You evil man...!

;-)

---* Bill

[gravatar]
kib2 10:08 AM on 26 Dec 2007

Hi Ned,

Thanks for pointing me this game, I became an addict now.
Did you find any links about a Python implementation about solving such diagrams ?

[gravatar]
jorge 2:53 AM on 27 Dec 2007

I have to agree with Bill

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