Fibonacci in Go

fibonacci.go

package main

import "fmt"

func fib(n int) (r int) {
	switch n {
	case 0:
		r = 0
	case 1:
		r = 1
	default:
		r = fib(n-1) + fib(n-2)
	}
	return
}

func fib2(n int) (r int) {
	r, acc := 0, 1
	for i := 0; i < n; i++ {
		r, acc = acc, r+acc
	}
	return
}

// Fib 3
func loop(n int) (r, acc int) {
	if n > 1 {
		r, acc = loop(n - 1)
		r, acc = r+acc, r
	} else {
		r, acc = n, n-1
	}
	return
}

func fib3(n int) int {
	r, _ := loop(n)
	return r
}

func main() {
	fmt.Print("Enter num: ")
	var input int
	fmt.Scanf("%d", &input)
	fmt.Printf("Fib(%d) = %d\n", input, fib3(input))
}