Day 13: Claw Contraption
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1 point
Nim
I’m embarrasingly bad with math. Couldn’t have solved this one without looking up the solution. =C
type Vec2 = tuple[x,y: int64]
const
PriceA = 3
PriceB = 1
ErrorDelta = 10_000_000_000_000
proc isInteger(n: float): bool = n.round().almostEqual(n)
proc `+`(a: Vec2, b: int): Vec2 = (a.x + b, a.y + b)
proc solveEquation(a, b, prize: Vec2): int =
let res_a = (prize.x*b.y - prize.y*b.x) / (a.x*b.y - a.y*b.x)
let res_b = (a.x*prize.y - a.y*prize.x) / (a.x*b.y - a.y*b.x)
if res_a.isInteger and res_b.isInteger:
res_a.int * PriceA + res_b.int * PriceB
else: 0
proc solve(input: string): AOCSolution[int, int] =
let chunks = input.split("\n\n")
for chunk in chunks:
let lines = chunk.splitLines()
let partsA = lines[0].split({' ', ',', '+'})
let partsB = lines[1].split({' ', ',', '+'})
let partsC = lines[2].split({' ', ',', '='})
let a = (parseBiggestInt(partsA[3]), parseBiggestInt(partsA[6]))
let b = (parseBiggestInt(partsB[3]), parseBiggestInt(partsB[6]))
let c = (parseBiggestInt(partsC[2]), parseBiggestInt(partsC[5]))
result.part1 += solveEquation(a,b,c)
result.part2 += solveEquation(a,b,c+ErrorDelta)
