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import kotlin.math.max
import kotlin.math.sign
object Day17 {
data class Target(val left: Int, val right: Int, val bottom: Int, val top: Int)
private class Probe(private var vel: Pos2D, private val target: Target) {
companion object {
fun search(target: Target): Pair<Int, Int> {
var highest = 0
var count = 0
for (vx in 0..1000) {
for (vy in -1000..1000) {
val probe = Probe(Pos2D(vx, vy), target)
var currentHighest = 0
while (probe.canHitTarget) {
probe.step()
currentHighest = max(currentHighest, probe.pos.y)
if (probe.isInTarget) {
count++
highest = max(highest, currentHighest)
break
}
}
}
}
return highest to count
}
}
private var pos = Pos2D(0, 0)
private fun step() {
pos += vel
vel = vel.copy(x = vel.x - vel.x.sign, y = vel.y - 1)
}
private val canHitTarget
get() = pos.y > target.bottom
private val isInTarget
get() = pos.x in target.left..target.right && pos.y in target.bottom..target.top
}
fun bothParts(input: Target) = Probe.search(input)
}
fun main() {
val testInput = Day17.Target(20, 30, -10, -5)
val testOutput = Day17.bothParts(testInput)
check(testOutput.first == 45)
check(testOutput.second == 112)
val input = Day17.Target(192, 251, -89, -59)
val output = Day17.bothParts(input)
println(output.first)
println(output.second)
}
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