Day 4: Ceres Search

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    1 year ago

    Uiua

    This one was nice. The second part seemed quite daunting at first but wasn’t actually that hard in the end.

    Run with example input here

    Row    ← ⌕ "XMAS"
    RevRow ← ⌕"SAMX"
    Sum    ← /+/+
    Count  ← +∩Sum⊃Row RevRow
    
    PartOne ← (
      &rs ∞ &fo "input-4.txt"
      ⊜∘≠@\n.
      ⊙+⟜∩Count⟜⍉ # horizontal and vertical search
      ⟜(/+⧈(Count⍉≡⬚@ ↻⇡⧻.)4)
      /+⧈(Count⍉≡⬚@ ↻¯⇡⧻.)4
      ++
    )
    
    Mask ← °⊚×2⇡5
    # Create variations of X-MAS
    Vars ← (
      ["M S"
       " A "
       "M S"]
      ≡♭[∩⟜⍉]≡⇌.
      Mask
      ⊏0⊞▽¤
    )
    
    PartTwo ← (
      &rs ∞ &fo "input-4.txt"
      ⊜∘≠@\n.
      ⧈(/+♭⊞≍⊙¤Vars▽Mask♭)3_3
      Sum
    )
    
    &p "Day 4:"
    &pf "Part 1: "
    &p PartOne
    &pf "Part 2: "
    &p PartTwo