Your first Sudoku-type puzzle

robert@fm · Posted: Wed Nov 01, 2006 8:58 pm Post subject: Your first Sudoku-type puzzle

I'm sure that in the UK, Keesing were there long before Nikoli! They used to publish 5x5 puzzles (marked into five pentominoes) with some squares coloured in as red, yellow, green, blue or violet, and the idea was to fill the rest of the squares with those colours such that each row, column and pentomino contained five different colours. This was about 10-15 years before the sudoku craze started! (They also published "Arrownumbers" -- like "Kakuro" but with the additional rule that each combination of digits may appear only once, e.g. if one 8 in two is 17 and another is 26, and there's a third, you know it must be 35 -- and "Round Trip", like today's "Loopy" puzzles except that the loop also has to pass through every dot, and the clues were existing line segments instead of numbers.)

The earliest Sudoku-type puzzle I can remember seeing was in 1966, in "The Second Pan Book of Puzzles" (last puzzle but one); it consisted of seven straight trominoes and two dominoes, with red, yellow, green, blue and white (five each, of course) distributed about their squares, and the object was to assemble them into a 5x5 square with each colour appearing once in every row and column. I finally solved it after twenty years(!) of trying, by having my Spectrum computer do a tree search of the puzzle's space; of course, by then I'd long-since lost the book. Smile

Does anyone else have any reminiscences?

isudoku · Posted: Wed Dec 27, 2006 5:04 am Post subject:

i heard of sudoku only this year. Very Happy