Erasable Games Weblog

(Sudoku in words and pictures)

Archive for August, 2008

Hidato™ On Sudoku

Monday, August 25th, 2008

Hidato On Sudoku

There’s been a significant increase in traffic to this blog ever since I posted the Numbrix™ puzzle variant at the end of July. For that, I thank you all for visiting.

This week, Barnes and Noble displayed a book by Dr. Gyora Benedek, called Hidato (A Hebrew word meaning: My Puzzle). Dr. Benedek writes an excellent (short) autobiography. The book itself contains variously sized and shaped grids including non-square (and non-quadrilateral) ones. Some web-based 10 x 10 grids have an interesting characteristic in that the middle 4 cells are darkened, indicating that they are not in play, leaving 96 cells to the playing area.

Hidato™ appears to be a generalization of Numbrix™ in two senses: Hidato™ distributes the starting numbers over the entire planar grid rather than at the edges and Hidato™ permits paths to be diagonal as well as horizontal and vertical. Both variants have the same objective, to fill in a path that sequentially leads from 1 to the ending number, thereby covering the entire grid without a sequence disconnection or duplication of numbers.

Having the horizontal, vertical and diagonal path choices for the next or previous number reminds me of the (computer) game called Minesweeper. In that game, you are faced with choosing the next cell that doesn’t have a mine hidden in it. In Hidato™, the choice is the next in the sequence being placed properly.

Typically, you’ll be connecting sequence segments based on the starting numbers. Luckily, the connectedness of the overall sequence requires that local neighborhoods of numbers be near in value. What provides a challenge is that It is possible that multiple such sequences may be intermixed.

The main site that publishes Hidato™ puzzles is, operated by Gameblend Studios, LLC. This site licenses daily Hidato™ puzzles of varying difficulty to a variety of web based sites, all marred by the same jarring soundtrack, which can eventually be turned off in the options.

I like the Seattle Times version of the Hidato™ site. Its Novice setting shows the next or previous missing number in the sequence on both the grid as well as a linear bar at the bottom of the grid, which is used to highlight any missing number for possible placements. It also offers a checking facility for a partial solution, to keep you on the right track.

On the negative side, there’s no facility for saving the current state of the puzzle (without printing it) and when you print the puzzle out, it does not let you return to the puzzle to continue with it.

See also an article dated July 31, 2008 by Ben Steelman for the about how Hidato™ evolved.

Have a good time with this variant. This is just the beginning for it.

Compact Sudoku

Monday, August 11th, 2008

Compact Sudoku

A while back, I created a Cartoon called Double Sudoku. In that variant, there were 2 totally separate Sudoku Puzzles embedded in a single Sudoku Grid with all split cells.

The current cartoon is reminiscent of that one, but has N-1 starting numbers that are the same for both puzzles. (Double Sudoku had all different starting numbers for each puzzle.)

In researching where this variant may exist on the internet, I came across a site called, by Dr. Chen, which has generalized this concept even further. Provided are puzzles with as many as 256 possible puzzles generated from multiple “Key Cells” in a single grid.

Normally, a “Key Cell” either contains a single digit M, which signifies that there are that (M) many puzzles bundled together (and you must figure out which digits lead to a solution) or the “Key Cell” contains multiple digits, which means that each of those digits leads to a different Sudoku puzzle.

Truly, this is a “Green” website for Sudoku Puzzles, where the number of Sudoku Grids is severely conserved. His site even offers multiple blank Sudoku grids that may be printed from a pdf or png formatted file.

I’ve provided tips for solving the above puzzle in the single grid by splitting blank cells in two parts. Of course, you can write each puzzle out on paper or duplicate electronically and solve each normally (and one after another).

I hope you enjoy solving this example of Sudoku puzzle cousins twice removed!

Plain Text Sudoku

Monday, August 4th, 2008

Plain Text Sudoku

This cartoon has at its root, a cartoon from 3/4/2007, called Linear Sudoku. For those that wish to describe a Sudoku puzzle to others, particularly by Email, the best way is to create either an 81 character text string or a 9 strings of size 9, where the dot represents the blank cell in both cases.

The site: Sudoku @ Paulspages permits the selection of a Sudoku puzzle, be it random, non-symmetric or from a gallery of puzzles and from that point, it is possible to export it as a text file as shown to the right of the Board in this Cartoon.

There are several benefits for this format, not the least of which is communicating with another puzzler to verify a difficulty or a solution. For those who are visually impaired, they can employ a software program that converts text to speech, thereby permitting the person to hear what the puzzle elements are, so that they can be solved mentally, or transcribed to a braille-writer for reference.

Now that text messaging is becoming most popular, these text strings can convey a puzzle in a minimum of words. This can be useful in timed competitions, where the winning solution is “texted” over to the contest judges for least time and solution correctness. See, for example:
Sudoku Text Challenge sponsored by the TimesOnline and retrieved June 17, 2008.