/
Day3.scala
104 lines (98 loc) · 2.85 KB
/
Day3.scala
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import scala.collection.mutable
object Day3 extends MultiPuzzle[Int, Int] {
override def part1(input: Iterator[String]): Int = {
val arr = input.toArray
var sum = 0
(0 until arr.length).foreach { i =>
var number = 0
var ongoingNumber = false
var detected = false
(0 until arr.head.length).foreach { j =>
val c = arr(i)(j)
if (c.isDigit) {
number = number * 10 + c.asDigit
ongoingNumber = true
// look at neighbors
for {
ii <- (i - 1) to (i + 1)
jj <- (j - 1) to (j + 1)
} {
if (ii != i || jj != j) {
if (ii >= 0 && ii < arr.length) {
if (jj >= 0 && jj < arr.head.length) {
if (!arr(ii)(jj).isDigit && arr(ii)(jj) != '.')
detected = true
}
}
}
}
} else {
if (ongoingNumber) {
if (detected)
sum += number
number = 0
}
ongoingNumber = false
detected = false
}
// handle end of line
if (j == arr.head.length - 1 && ongoingNumber && detected) {
sum += number
}
}
}
sum
}
override def part2(input: Iterator[String]): Int = {
val arr = input.toArray
val m = mutable.Map[(Int, Int), mutable.ListBuffer[Int]]()
(0 until arr.length).foreach { i =>
var number = 0
var ongoingNumber = false
var detected = mutable.Set[(Int, Int)]()
(0 until arr.head.length).foreach { j =>
val c = arr(i)(j)
if (c.isDigit) {
number = number * 10 + c.asDigit
ongoingNumber = true
// look at neighbors
for {
ii <- (i - 1) to (i + 1)
jj <- (j - 1) to (j + 1)
} {
if (ii != i || jj != j) {
if (ii >= 0 && ii < arr.length) {
if (jj >= 0 && jj < arr.head.length) {
if (arr(ii)(jj) == '*')
detected.addOne((ii, jj))
}
}
}
}
} else {
if (ongoingNumber) {
detected.foreach { pos =>
if (!m.isDefinedAt(pos)) {
m(pos) = mutable.ListBuffer[Int]()
}
m(pos).addOne(number)
}
number = 0
}
ongoingNumber = false
detected = mutable.Set[(Int, Int)]()
}
// handle end of line
if (j == arr.head.length - 1 && ongoingNumber) {
detected.foreach { pos =>
if (!m.isDefinedAt(pos)) {
m(pos) = mutable.ListBuffer[Int]()
}
m(pos).addOne(number)
}
}
}
}
m.collect { case (_, v) if v.size == 2 => v.product }.sum
}
}