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Sudoku: Difference between revisions
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(7 5 9 2 3 8 1 4 6)
(8 2 6 4 1 9 7 3 5))</pre>
=={{header|Curry}}==
Copied from [http://www.informatik.uni-kiel.de/~curry/examples/ Curry: Example Programs].
<lang curry>
-----------------------------------------------------------------------------
--- Solving Su Doku puzzles in Curry with FD constraints
---
--- @author Michael Hanus
--- @version December 2005
-----------------------------------------------------------------------------
import CLPFD
import List
-- Solving a Su Doku puzzle represented as a matrix of numbers (possibly free
-- variables):
sudoku :: [[Int]] -> Success
sudoku m =
domain (concat m) 1 9 & -- define domain of all digits
foldr1 (&) (map allDifferent m) & -- all rows contain different digits
foldr1 (&) (map allDifferent (transpose m)) & -- all columns have different digits
foldr1 (&) (map allDifferent (squaresOfNine m)) & -- all 3x3 squares are different
labeling [FirstFailConstrained] (concat m)
-- translate a matrix into a list of small 3x3 squares
squaresOfNine :: [[a]] -> [[a]]
squaresOfNine [] = []
squaresOfNine (l1:l2:l3:ls) = group3Rows [l1,l2,l3] ++ squaresOfNine ls
group3Rows l123 = if null (head l123) then [] else
concatMap (take 3) l123 : group3Rows (map (drop 3) l123)
-- read a Su Doku specification written as a list of strings containing digits
-- and spaces
readSudoku :: [String] -> [[Int]]
readSudoku s = map (map transDigit) s
where
transDigit c = if c==' ' then x else ord c - ord '0'
where x free
-- show a solved Su Doku matrix
showSudoku :: [[Int]] -> String
showSudoku = unlines . map (concatMap (\i->[chr (i + ord '0'),' ']))
-- the main function, e.g., evaluate (main s1):
main s | sudoku m = putStrLn (showSudoku m)
where m = readSudoku s
s1 = ["9 2 5 ",
" 4 6 3 ",
" 3 6",
" 9 2 ",
" 5 8 ",
" 7 4 3",
"7 1 ",
" 5 2 4 ",
" 1 6 9"]
s2 = ["819 5 ",
" 2 75 ",
" 371 4 6 ",
"4 59 1 ",
"7 3 8 2",
" 3 62 7",
" 5 7 921 ",
" 64 9 ",
" 2 438"]
</lang>
=={{header|D}}==
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