feat: 添加商品数据结构和计算功能

- 创建 Product 和 ProductGroup 类型定义- 实现商品列表初始化及分类逻辑
- 添加价格转换为货币格式的功能
- 实现按类别计算子总额与总金额功能
- 创建主函数调用并展示总额计算结果

14-concurrency/concurrency/go.mod

@@ -0,0 +1,3 @@
+module concurrency
+
+go 1.22

14-concurrency/concurrency/main.go

@@ -0,0 +1,9 @@
+package main
+
+import "fmt"
+
+func main() {
+	fmt.Println("main function started")
+	CalcStoreTotal(Products)
+	fmt.Println("main function complete")
+}

14-concurrency/concurrency/operations.go

@@ -0,0 +1,19 @@
+package main
+
+import "fmt"
+
+func CalcStoreTotal(data ProductData) {
+	var storeTotal float64
+	for category, group := range data {
+		storeTotal += group.TotalPrice(category)
+	}
+	fmt.Println("Total: ", ToCurrency(storeTotal))
+}
+
+func (group ProductGroup) TotalPrice(category string) (total float64) {
+	for _, p := range group {
+		total += p.Price
+	}
+	fmt.Println(category, "subtotal: ", ToCurrency(total))
+	return
+}

14-concurrency/concurrency/product.go

@@ -0,0 +1,39 @@
+package main
+
+import "strconv"
+
+type Product struct {
+	Name, category string
+	Price          float64
+}
+
+type ProductGroup []*Product
+
+var ProductList = []*Product{
+	{"Kayak", "Watersports", 279},
+	{"LifeJacket", "Watersports", 49.95},
+	{"Soccer Ball", "Soccer", 19.50},
+	{"Corner Flags", "Soccer", 34.95},
+	{"Stadium", "Soccer", 79500},
+	{"Thinking Cap", "Chess", 16},
+	{"Unsteady Chair", "Chess", 29.95},
+	{"Bling-Bling King", "Chess", 1200},
+}
+
+type ProductData = map[string]ProductGroup
+
+var Products = make(ProductData)
+
+func ToCurrency(price float64) string {
+	return "$" + strconv.FormatFloat(price, 'f', 2, 64)
+}
+
+func init() {
+	for _, product := range ProductList {
+		if _, ok := Products[product.category]; ok {
+			Products[product.category] = append(Products[product.category], product)
+		} else {
+			Products[product.category] = ProductGroup{}
+		}
+	}
+}