Knight's tour: Difference between revisions
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(→{{header|Haskell}}: Slight disaggregation, pruned out some surplus magic from a list.) |
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=={{header|Haskell}}== |
=={{header|Haskell}}== |
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<lang Haskell> |
<lang Haskell>{-# LANGUAGE TupleSections #-} |
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import Data.List (minimumBy, (\\), intercalate, sort) |
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import Data.Ord (comparing) |
import Data.Ord (comparing) |
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import Data.Char (ord, chr) |
import Data.Char (ord, chr) |
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newSquare = minimumBy (comparing (length . findMoves)) possibilities |
newSquare = minimumBy (comparing (length . findMoves)) possibilities |
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possibilities = findMoves $ head moves |
possibilities = findMoves $ head moves |
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findMoves = (\\ moves) . |
findMoves = (\\ moves) . knightOptions |
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knightOptions :: Square -> [Square] |
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knightOptions (x, y) = |
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knightMoves >>= |
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[(1, 2), (1, -2), (-1, 2), (-1, -2), (2, 1), (2, -1), (-2, 1), (-2, -1)] >>= |
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(\(i, j) -> |
(\(i, j) -> |
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let a = x + i |
let a = x + i |
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b = y + j |
b = y + j |
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in bool [] [(a, b)] (onBoard a && onBoard b)) |
in bool [] [(a, b)] (onBoard a && onBoard b)) |
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knightMoves :: [(Int, Int)] |
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knightMoves = |
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let deltas = (<$> [1, 2]) =<< [id, negate] |
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in deltas >>= |
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(\i -> deltas >>= (bool [] . return . (i, )) <*> ((abs i /=) . abs)) |
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onBoard :: Int -> Bool |
onBoard :: Int -> Bool |
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