27 lines
838 B
Nix
27 lines
838 B
Nix
with import ../util.nix;
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let
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# read input
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input = readFile ./input;
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pairs = let
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readRange = s: splitPair (a: b: [ (toInt a) (toInt b) ]) (splitString "-" s);
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readPair = a: b: [ (readRange a) (readRange b) ];
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in map
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(line: splitPair readPair (splitString "," line))
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(splitString "\n" input);
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# overlap functions
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partialOverlap = a1: a2: b1: b2:
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a1 <= b1 && b1 <= a2 || a1 <= b2 && b2 <= a2;
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completeOverlap = a1: a2: b1: b2:
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a1 <= b1 && a2 >= b2;
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# calc overlaps
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hasOverlap = overlapFunc: a: b:
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let a1 = head a; b1 = head b; a2 = last a; b2 = last b;
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in overlapFunc a1 a2 b1 b2 || overlapFunc b1 b2 a1 a2;
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overlaps = overlapFunc: map boolToInt (map (splitPair (hasOverlap overlapFunc)) pairs);
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in {
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part1 = sum (overlaps completeOverlap);
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part2 = sum (overlaps partialOverlap);
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} |