おれなにやってんだろ.kt

data class Ret(val count:Int, val prev:Int?) {
  fun next(number:Int) = if (prev == number)
    Ret(count, number)
  else
    Ret(count + 1, number)
}

fun runs(a: IntArray): Int {
  return a.fold(Ret(0, null), {(ret, num) ->
    ret.next(num)
  }).count
}