RosettaCodeData/Task/Ackermann-function/Kotlin/ackermann-function.kts

26 lines
737 B
Kotlin

tailrec fun A(m: Long, n: Long): Long {
require(m >= 0L) { "m must not be negative" }
require(n >= 0L) { "n must not be negative" }
if (m == 0L) {
return n + 1L
}
if (n == 0L) {
return A(m - 1L, 1L)
}
return A(m - 1L, A(m, n - 1L))
}
inline fun<T> tryOrNull(block: () -> T): T? = try { block() } catch (e: Throwable) { null }
const val N = 10L
const val M = 4L
fun main() {
(0..M)
.map { it to 0..N }
.map { (m, Ns) -> (m to Ns) to Ns.map { n -> tryOrNull { A(m, n) } } }
.map { (input, output) -> "A(${input.first}, ${input.second})" to output.map { it?.toString() ?: "?" } }
.map { (input, output) -> "$input = $output" }
.forEach(::println)
}