a.get(i + 1)で落ちる(´・ω・｀)

(´・ω・｀).kt

package yank

fun runs(a: IntArray): Int {
  return a.answer({(i: Int): Boolean -> i < a.size && a.get(i) != a.get(i + 1) })
}

fun IntArray.answer(filter: (i: Int) -> Boolean): Int {
  var result =
      when (this.size) {
        0 -> 0
        else -> 1
      }
  for (i in this.indices) {
    if (filter(i)) {
      result++
    }
  }
  return result
}

fun main(args: Array<String>) {
  println (runs(intArray(1, 2, 3, 2, 1)))
}