Linear/2 Sum Function

main.go

package main

import "fmt"
import "math"

func CalcSum(numbers []int, left int, right int) int {
	aFinished := make(chan int)
	bFinished := make(chan int)

	mid := int(math.Floor(float64(len(numbers)) / float64(2)))

	// a reads from index 0 (inclusive) to the middle (exclusive)
	go func() {
		asum := 0
		for i := left; i < mid; i++ {
			asum += numbers[i]
		}

		aFinished <- asum
	}()

	// b reads from index end (inclusive) to the mid
	go func() {
		bsum := 0
		for i := len(numbers) - 1; i >= mid; i-- {
			bsum += numbers[i]
		}

		bFinished <- bsum
	}()

	return <-aFinished + <-bFinished
}

func main() {
	numbers := []int{1, 5, 2, 7, 1, 9}
	fmt.Println(CalcSum(numbers, 0, len(numbers)))
}