Day6.scala

package sungkmi.aoc2020.day6

def grouping(input: String): Seq[String] = input.split("\n\n").toSeq

def count(reduceRule: (Set[Char], Set[Char]) => Set[Char])(groupString: String): Int =
  groupString
    .split("\n")
    .map(_.toSet)
    .reduce(reduceRule)
    .size

def sumOfCount(input: String): Int = grouping(input).map(count(_ ++ _)).sum

def sumOfCount2(input: String): Int = grouping(input).map(count(_ `intersect` _)).sum

@main def part1: Unit =
  val ans = sumOfCount(input)
  println(ans)

@main def part2: Unit =
  val ans = sumOfCount2(input)
  println(ans)

//lazy val input = """jmqnkzlsfedaptx

Day6Test.scala

package sungkmi.aoc2020.day6

class Day6Test extends munit.FunSuite {
  val input = """abc

a
b
c

ab
ac

a
a
a
a

b"""

  test("sumOfCount") {
    assertEquals(sumOfCount(input), 11)
  }

  test("sumOfCount2") {
    assertEquals(sumOfCount2(input), 6)
  }
}