fibo_monica

//1.create file name : main.go 2.paste the code 3. run : go run main.go | don't forget to download go : https://go.dev/

package main

import (
    "fmt"
    "math"
)

func fibonacci(n int) int64 {
    if n <= 0 {
        return 0
    }
    sqrt5 := math.Sqrt(5)
    phi := (1 + sqrt5) / 2
    psi := (1 - sqrt5) / 2
    //สูตร (φ^n - ψ^n) / √5
    result := (math.Pow(phi, float64(n)) - math.Pow(psi, float64(n))) / sqrt5
    return int64(math.Round(result))
}

func main() {
    for {
        fmt.Print("Enter value: ")
        var num int
        if _, err := fmt.Scanln(&num); err != nil || num <= 0 {
            break
        }
        answer := fibonacci(num)

        fmt.Printf("Result of %d is: %d\n", num, answer)
    }
}