part04.kap

∇ solvePart1 {
  stringToNumbers ⇐ {⍎¨ ⍵ ⊂⍨ ⍺≠⍵}

  filecontent ← io:read "part04.txt"
  num ← @, stringToNumbers ↑filecontent
  b ← ⊃ {⊃ (↑" ") stringToNumbers¨ ⍵}¨ v ⊂⍨ (⊂⍬) ≢¨ v←2↓filecontent

  ⍝ Compute the time at which each cell is picked, 0 means that the cell was not picked
  indexed ← (1+⍳≢num) ×⌺ (⍴b)⍴1
  res ← +⌿ indexed × num=⌺b

  highest ← ⌊/ (⌊/⌈/[2] res) ,[0.5] ⌊/⌈/[1] res
  winning ← b[indexHigh←↑⍋highest;;]
  numbersPicked ← highest[indexHigh]

  unmarkedValues ← winning × ~winning ∊ num[⍳numbersPicked]
  num[numbersPicked-1] × +/,unmarkedValues
}