Sunday 23 December 2007This is over 15 years old. Be careful.

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.


This is also included in Simon Tatham's portable puzzle collection, along with loads of others.
Yikes. Just when I was kicking my suduko habit. You evil man...!


---* Bill
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 ?
I have to agree with Bill
For all who like this game, I just found a good iPhone implementation (rules are a little different/maybe easier but I like it): https://itunes.apple.com/us/app/trestle/id1300230302?ls=1&mt=8

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