Two sum: Difference between revisions
Content added Content deleted
m (→ES6: Minor simplification) |
(→JS ES6: Added comments on access to indices, and skipping the 'lower triangle' of a cartesian grid (where iy < ix)) |
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| Line 244: | Line 244: | ||
// summingPairIndices :: -> Int -> [Int] -> [(Int, Int)] |
// summingPairIndices :: -> Int -> [Int] -> [(Int, Int)] |
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let summingPairIndices = (n, xs) => |
let summingPairIndices = (n, xs) => |
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// Javascript map functions have access to the array index |
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// in their second argument. |
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concatMap((x, ix) => concatMap((y, iy) => |
concatMap((x, ix) => concatMap((y, iy) => |
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iy |
iy < ix ? [] : ( // Ignoring mirror-image tuples by |
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// skipping the 'lower triangle' (y < x) |
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// of the cartesian product grid |
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x + y === n ? [ |
x + y === n ? [ |
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[ |
[ix, iy] |
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] : [] |
] : [] |
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), xs), xs); |
), xs), xs); |
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