第三章课后作业

# 三级菜单;
# 省、市、县  可随时返回上一级(b)，可以随时退出(q)；
add_dest={'jiangsu': {'wuxi': ['宜兴', 'jiangying', 'xishan'], 'nanjing': ['qixia', 'gulou', 'changning', 'zhongshan']},
'zhejiang': {'嘉兴': ['a2', 'a3', 'a4'],'宁波': ['a1', 'a2', 'a3']},
'guangzhou': {1: ['a'], 2: ['b'], 3: ['c']}
}
break_flag = Falsewhile break_flag == False:
    print("可选择省份:")
    for i in add_dest:
        print(i)
    pick_add = input("选择省份：")
    if pick_add == 'q':
        break
    while pick_add in add_dest and break_flag == False:
        print("可选择的市:")
        for k in add_dest[pick_add]:
            print(k)
        pick_add2 = input("选择市：")
        if pick_add2 in add_dest[pick_add]:
            print("您的目的地是：%s"%pick_add2)
        elif pick_add2 == 'b':
            break
        elif pick_add2 == 'q':
            break_flag = True
            break
        while pick_add2 in add_dest[pick_add]:
            print("可选择的县:")
            for j in add_dest[pick_add][pick_add2]:
                print(j)
            pick_add3 = input("最终目的地:")
            if pick_add3 in add_dest[pick_add][pick_add2]:
                print("您的最终目的地是：%s"%pick_add3)
                pick_add4 = input("按b返回，按q退出:")
                if pick_add4 == 'b':
                    continue
                if pick_add4 == 'q':
                    exit()
            elif pick_add3 == 'b':
                break
            elif pick_add3 == 'q':
                break_flag = True
                break

KEY菜单用while循环：好处是输入有误自动再次循环;如果用for循环key 需要判断几个其他情况的条件;

value处用for循环

break_flag用于熟悉使用;

三级菜单优化：不同之处：最后一级是字典，（原最后一级是数组;）

menu={'jiangsu': {'wuxi': {'宜兴':{'官林':{}}, 'jiangying':{}, 'xishan':{}}, 'nanjing': {'qixia', 'gulou', 'changning', 'zhongshan'}},
'zhejiang': {'嘉兴': {'a2', 'a3', 'a4'},'宁波': {'a1', 'a2', 'a3'}},
'guangzhou': {1: {'a'}, 2: {'b'}, 3:{'c'}}
}

last_layers=[menu]
current_layer = menu
while True:
    for i in current_layer:
        print(i)
    choice = input(">>:").strip()
    if len(choice)==0:continue
    if choice in current_layer:
        last_layers.append(current_layer)
        # print (last_layers)
        current_layer = current_layer[choice] #下一层;
        print (current_layer)
    if choice == 'b':
        if last_layers:
            current_layer = last_layers[-1]
            last_layers.pop()

购物车优化：

your_cart=[]
cart={}
product_list=[['iphone',5000],['book',50],['bike',1500],['coffee',30],['ticket',80]]
salary = input('pls input your salary:')
ct = 1
if salary.isdigit():
    salary = int(salary)
    # 如果输入的是0-9字符串类型的数字;(它是数字，只不过是字符串形式)那么认为是真！然后转int类型;
    while True:
        for i in enumerate(product_list):
            print(i)
        your_choice = input("pls pick your favorite stuff:")
        if your_choice.isdigit():
            your_choice = int(your_choice)
            if your_choice <len(product_list) and your_choice >=0:
                product = product_list[your_choice]
                print(product)
                if product_list[your_choice][1]<=salary:
                    if product_list[your_choice][0] in cart:
                        cart[product[0]][1] += 1                                     #计数
                        salary = salary - product_list[your_choice][1]
                        print("in your_cart:%s,and money left:%s"%(cart,salary))
                    else:
                        cart[product[0]] = [product[1],1]
                        # print(cart)
                        salary = salary - product_list[your_choice][1]
                        print("in your_cart:%s,and money left:%s"%(cart,salary))

                else:
                    print("not enough money!")

            else:
                print("your choice is not exit.")
                continue
        elif your_choice == 'q':
            print("序号:","商品:","单价:","数量:","单项总价:")
　　　　　　　totalcost=0
            for i in (cart):
                print(ct,i,cart[i][0],cart[i][1],cart[i][1]*cart[i][0])
                ct +=1
　　　　　　　　　 totalcost +=cart[i][1]*cart[i][0]
                print("总花费:%s"%totalcost)
            break
        # elif your_choice == "\n\t":                                           #python遇到回车默认结束！
        #     print("in your_cart:%s,and money left:%s"%(cart,salary))
        #     # elif your_choice == 'manager':
            #     print("welcome manager")
            #     add_product = input("goods %s,price %s"%(goods,price))