Better parallel version

Author: rafax

10pp.go

@@ -0,0 +1,38 @@
+package main
+
+import (
+	"./utils"
+	"fmt"
+	"runtime"
+	"sync"
+)
+
+func main() {
+	runtime.GOMAXPROCS(runtime.NumCPU())
+	max := 2000000
+	primes := findPrimes(max)
+	sum := 2
+	for i := range primes {
+		sum += i
+	}
+	fmt.Println(sum)
+}
+
+func findPrimes(max int) <-chan int {
+	primes := make(chan int, max)
+	var done sync.WaitGroup
+	for i := 3; i < max; i += 2 {
+		done.Add(1)
+		go func(num int) {
+			if utils.IsPrime(num) {
+				primes <- num
+			}
+			done.Done()
+		}(i)
+	}
+	go func() {
+		done.Wait()
+		close(primes)
+	}()
+	return primes
+}