16 lines
540 B
Kotlin
16 lines
540 B
Kotlin
fun middleThree(x: Int): Int? {
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val s = Math.abs(x).toString()
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return when {
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s.length < 3 -> null // throw Exception("too short!")
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s.length % 2 == 0 -> null // throw Exception("even number of digits")
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else -> ((s.length / 2) - 1).let { s.substring(it, it + 3) }.toInt()
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}
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}
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fun main(args: Array<String>) {
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println(middleThree(12345)) // 234
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println(middleThree(1234)) // null
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println(middleThree(1234567)) // 345
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println(middleThree(123))// 123
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println(middleThree(123555)) //null
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}
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