Solve a Holy Knight's tour: Difference between revisions

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const problems = [

[

" 000 " //

, " 0 00 " //

, " 0000000" //

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],

[

"-----1-0-----" //

, "-----0-0-----" //

, "----00000----" //

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return unit.concat.apply(unit, xs);

})() : [];

⚫

// charColRow :: Char -> [String] -> Maybe (Int, Int)

⚫

const charColRow = (c, rows) =>

⚫

foldr((a, xs, iRow) =>

⚫

a.nothing ? (() => {

⚫

const mbiCol = elemIndex(c, xs);

⚫

return mbiCol.nothing ? mbiCol : {

⚫

just: [mbiCol.just, iRow],

nothing: false

⚫

};

⚫

})() : a, {

nothing: true

⚫

}, rows);

// 2 or more arguments

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// elem :: Eq a => a -> [a] -> Bool

const elem = (x, xs) => xs.indexOf(x) !== -1;

// elemIndex :: Eq a => a -> [a] -> Maybe Int

const elemIndex = (x, xs) => {

⚫

const i = xs.indexOf(x);

return {

nothing: i === -1,

just: i

⚫

};

// enumFromTo :: Int -> Int -> [Int]

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// foldl :: (b -> a -> b) -> b -> [a] -> b

const foldl = (f, a, xs) => xs.reduce(f, a);

// foldr (a -> b -> b) -> b -> [a] -> b

const foldr = (f, a, xs) => xs.reduceRight(f, a);

// groupBy :: (a -> a -> Bool) -> [a] -> [[a]]

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return v;

};

// zip :: [a] -> [b] -> [(a,b)]

const zip = (xs, ys) =>

xs.slice(0, Math.min(xs.length, ys.length))

.map((x, i) => [x, ys[i]]);

// zipWith :: (a -> b -> c) -> [a] -> [b] -> [c]

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const hash = ([col, row]) => col.toString() + '.' + row.toString();

⚫

// ~~startPosn~~ :: [String] -> Maybe (Int, Int)

⚫

const ~~startPosn~~ = rows => {

⚫

const mb = ~~findIndex(s => s~~.indexOf(~~'1') !== -1, rows~~);

⚫

return mb.nothing ? {

⚫

nothing: ~~true~~

⚫

} : (() => {

⚫

const ~~iRow~~ = ~~mb.just~~;

⚫

~~return~~ [

findIndex(s => s === '1', rows[iRow])

.just, iRow

];

})();

};

// Start node, and degree-sorted cache of moves from each node

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);

return {

start: hash(~~startPosn~~(boardLines)),

start: hash(charColRow('1', boardLines)

.just),

boardWidth: boardLines.length > 0 ? boardLines[0].length : 0,

stepCount: steps.length,