Advent of Code 2023-1.scala

import java.io.FileInputStream
import scala.io.StdIn

def solve1_1(values: Vector[String]): Int =
  values.map(x => {
    val firstNumber = x.find(_.isDigit).get
    val lastNumber = x.findLast(_.isDigit).get
    s"$firstNumber$lastNumber".toInt
  }).sum


def convertToNumber(s: String, index: Int): Option[Int] =
  val numberStrings = Array("one", "two", "three", "four", "five", "six", "seven", "eight", "nine")

  if s(index).isDigit then
    Some(s(index).toString.toInt)
  else
    numberStrings.zipWithIndex.collectFirst({
      case pair if s.startsWith(pair._1, index) =>
        pair._2 + 1
    })

def solve1_2(values: Vector[String]): Int =
  values.map(x => {
    val numbers = x.indices.flatMap(convertToNumber(x, _))
    val firstNumber = numbers.head
    val lastNumber = numbers.last
    firstNumber * 10 + lastNumber
  }).sum

@main def solve1(): Unit =
  val in = new FileInputStream("example1-2.in")
  System.setIn(in)
  val inputs = Iterator.continually(StdIn.readLine())
    .takeWhile(line => null != line)
    .toVector
  println(solve1_1(inputs))
  println(solve1_2(inputs))