Day 4: Scratchcards


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  • @[email protected]
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    1 year ago

    APL

    I’m using this years’ AoC to learn (Dyalog) APL, so this is probably terrible code. I’m happy to receive pointers for improvement, particularly if there is a way to write the same logic with tacit functions or inner/outer products that I missed.

    input←⊃⎕NGET'inputs/day4.txt'1
    num_matches←'Card [ \d]+: ([ 0-9]+) \| ([ 0-9]+)'⎕S{≢↑∩/0~⍨¨{,⎕CSV⍠'Separator' ' '⊢⍵'S'3}¨⍵.(1↓Lengths↑¨Offsets↓¨⊂Block)} input
    ⎕←+/2*1-⍨0~⍨num_matches ⍝ part 1
    ⎕←+/{⍺←0 ⋄ ⍺=≢⍵:⍵ ⋄ (⍺+1)∇⍵ + (≢⍵)↑∊((⍺+1)⍴0)(num_matches[⍺]⍴⍵[⍺])((≢⍵)⍴0)}(≢num_matches)⍴1 ⍝ part 2
    
    • @mykl
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      21 year ago

      I just posted a solution in Uiua, which is also probably equally terrible, but if you squint you can see some similarities in our approaches.

      • @[email protected]
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        21 year ago

        I haven’t heard of Uiua before, but I can read some things :D I like the idea of rotating the vector instead of manually padding it with the required number of leading zeroes!

        • @mykl
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          11 year ago

          I think it’s only a few months old. I’ve enjoyed playing with it because it allows me to use stack manipulation as an alternative to combinators and every symbol has a fixed arity both of which make it feel a lot more accessible to me.

          I was very pleased with myself when I thought of that rotation trick :-)