add: 211231-CN multi-threaded searching

2112/211231-CN.cpp

@@ -29,3 +29,88 @@ int main() {
 	}
 	return 0;
 }
+
+/**
+ * Use this golang program to do multi-threaded searching:
+ *
+package main
+
+import (
+	"fmt"
+	"math"
+	"sync"
+	"time"
+)
+
+type taskArgument struct {
+	L uint32
+	R uint32
+}
+
+var (
+	tasks        = make(chan taskArgument)
+	printContent = make(chan string)
+)
+
+const (
+	step  = 500000
+	limit = 100000000
+)
+
+func taskExecutor(mutex *sync.Mutex) {
+	mutex.Lock()
+	defer mutex.Unlock()
+	for {
+		args, ok := <-tasks
+		if !ok {
+			return
+		}
+		for i := args.L; i <= args.R; i++ {
+			var s uint32 = 1
+			lim := uint32(math.Sqrt(float64(i) + 0.5))
+			for j := uint32(2); j <= lim; j++ {
+				if i%j == 0 {
+					s += j + i/j
+				}
+			}
+			if s == i {
+				printContent <- fmt.Sprintf("%d", i)
+			}
+		}
+		printContent <- fmt.Sprintf("Finishing searching [%d, %d]", args.L, args.R)
+	}
+}
+
+func main() {
+	go Printer()
+	threads := 20
+	locks := make([]sync.Mutex, threads)
+	start := time.Now()
+	for i := 0; i < threads; i++ {
+		go taskExecutor(&locks[i])
+	}
+	for i := 1; i < limit; i += step {
+		tasks <- taskArgument{
+			L: uint32(i),
+			R: uint32(i + step - 1),
+		}
+	}
+	close(tasks)
+	time.Sleep(1 * time.Second)
+	for i := 0; i < threads; i++ {
+		locks[i].Lock()
+	}
+	end := time.Now()
+	fmt.Println(end.Sub(start))
+}
+
+func Printer() {
+	for {
+		s, ok := <-printContent
+		if !ok {
+			return
+		}
+		fmt.Println(s)
+	}
+}
+ */