Recursive vs Iterative with #Kotlin and #Fibonacci sequence

fibonacci.kt

import java.time.Duration
import java.time.Instant

object Fibonacci {
    fun recursive(n: Long): Long = if (n < 2) n else recursive(n - 1) + recursive(n - 2)

    tailrec fun recursiveTail(n: Long, a: Long, b: Long): Long
            = if (n < 1) a else recursiveTail(n - 1, b, a + b)

    fun iterative(n: Long): Long {
        if (n < 2) return n
        var minusOne: Long = 1
        var minusTwo: Long = 0
        var result = minusOne
        for (i in 2..n) {
            result = minusOne + minusTwo
            minusTwo = minusOne
            minusOne = result
        }
        return result
    }
}

fun main(args: Array<String>) {
    println("Fibonacci recursive vs iterative")

    measure(Fibonacci::recursive, 50)
    measure(Fibonacci::recursiveTail, 5000, 0, 1)
    measure(Fibonacci::iterative, 5000)
}

fun measure(method: (n: Long, a: Long, b: Long) -> Long, n: Long, a: Long, b: Long) {
    val start = Instant.now()
    val result = method(n, a, b)
    val finish = Instant.now()
    val timeElapsed = Duration.between(start, finish).toMillis()
    print("\nFibonacci($n) = $result Time elapsed: $timeElapsed ms")
}

fun measure(method: (n: Long) -> Long, n: Long) {
    val start = Instant.now()
    val result = method(n)
    val finish = Instant.now()
    val timeElapsed = Duration.between(start, finish).toMillis()
    print("\nFibonacci($n) = $result Time elapsed: $timeElapsed ms")
}

Output:
Fibonacci recursive vs iterative

Fibonacci(50) = 12586269025 Time elapsed: 46094 ms
Fibonacci(5000) = 535601498209671957 Time elapsed: 1 ms
Fibonacci(5000) = 535601498209671957 Time elapsed: 0 ms