recursion02.go

package main

import (
	"fmt"
	"time"
)

// Slow version
func sumOfArraySlow(arr []int) int {

	if len(arr) == 0 {
		return 0
	}

	rest := arr[1:]

	return arr[0] + sumOfArraySlow(rest)
}

// Fast version
func sumOfArrayFast(arr []int) int {

	return helperSum(arr, 0)
}

func helperSum(arr []int, index int) int {

	if len(arr) == index {
		return 0
	}

	return arr[index] + helperSum(arr, index+1)
}

func main() {

	input := make([]int, 9000)

	for i := range input {
		input[i] = 1
	}

	now := time.Now()

	fmt.Println(sumOfArraySlow(input))

	finish := time.Since(now)

	fmt.Println("time elapsed for slowFunction:", finish)

	start := time.Now()

	fmt.Println(sumOfArrayFast(input))

	end := time.Since(start)

	fmt.Println("time elapsed for fastFunction:", end)
}