三级菜单练习

# incoding=gbk

menu = {
    'A':{'a':1, 'b':2, 'c':3},
    'B':{'d':1, 'e':2, 'f':3},
    'C':{'h':1, 'i':2, 'j':3},
    }

flag = True

while flag:
    while flag:
        for i in menu:
            print(i)
        msg_1 = input(">>>")
        if msg_1 == 'q':
            flag = False
        elif msg_1 == 'back':
            break
        elif msg_1 == 'A':
            while flag:
                for j in menu[msg_1]:
                    print(j)
                msg_2 = input(">>>")
                if msg_2 == 'q':
                    flag = False
                elif msg_2 == 'back':
                    break
                elif msg_2 == 'a':
                    print(menu[msg_1][msg_2])
                    break
                elif msg_2 == 'b':
                    print(menu[msg_1][msg_2])
                elif msg_2 == 'c':
                    print(menu[msg_1][msg_2])
                else:
                    print("输入有误，请重新输入！")
                    continue
        elif msg_1 == 'B':
            while flag:
                for j in menu[msg_1]:
                    print(j)
                msg_2 = input(">>>")
                if msg_2 == 'q':
                    flag = False
                elif msg_2 == 'back':
                    break
                elif msg_2 == 'd':
                    print(menu[msg_1][msg_2])
                elif msg_2 == 'e':
                    print(menu[msg_1][msg_2])
                elif msg_2 == 'f':
                    print(menu[msg_1][msg_2])
                else:
                    print("输入有误，请重新输入！")
                    continue
        elif msg_1 == 'C':
            while flag:
                for j in menu[msg_1]:
                    print(j)
                msg_2 = input(">>>")
                if msg_2 == 'q':
                    flag = False
                elif msg_2 == 'back':
                    break
                elif msg_2 == 'h':
                    print(menu[msg_1][msg_2])
                elif msg_2 == 'i':
                    print(menu[msg_1][msg_2])
                elif msg_2 == 'j':
                    print(menu[msg_1][msg_2])
                else:
                    print("输入有误，请重新输入！")
                    continue
        else:
            print("输入有误，请重新输入！")
            continue