只用python写出一个简易火车售票系统，车辆等信息要用字典输入，要有注册，浏览，购买，改签和退票的功能，要显示多个车次每个车次要有不同的座位，不同的价格，可以一次性购买多张票，要有余票限制，车次时间，和起点站，终点站，购买完成之后要显示订单，代码

好的，我会尽力来写一个简易的火车售票系统，以下是代码：

# 火车售票系统

# 车辆信息
trains = {'G1': {'time': '8:00', 'start': '北京', 'end': '上海', 'price': 1000, 'seats': 100},
          'G2': {'time': '9:00', 'start': '上海', 'end': '北京', 'price': 1000, 'seats': 100},
          'G3': {'time': '10:00', 'start': '北京', 'end': '广州', 'price': 1500, 'seats': 50},
          'G4': {'time': '11:00', 'start': '广州', 'end': '北京', 'price': 1500, 'seats': 50},
          'G5': {'time': '12:00', 'start': '北京', 'end': '深圳', 'price': 2000, 'seats': 20},
          'G6': {'time': '13:00', 'start': '深圳', 'end': '北京', 'price': 2000, 'seats': 20}}

# 用户信息
users = []


# 注册函数
def register():
    name = input("请输入您的姓名：")
    id_card = input("请输入您的身份证号：")
    user = {'name': name, 'id_card': id_card, 'orders': []}
    users.append(user)
    print("注册成功！")


# 浏览函数
def show_trains():
    for train in trains:
        print(train, "出发时间：", trains[train]['time'], "起点：", trains[train]['start'],
              "终点：", trains[train]['end'], "票价：", trains[train]['price'], "余票：", trains[train]['seats'])


# 购买函数
def buy_ticket(user):
    train_id = input("请输入车次：")
    if train_id not in trains:
        print("输入错误！")
        return
    train = trains[train_id]
    seat_count = int(input("请输入购票数量："))
    if seat_count > train['seats']:
        print("余票不足！")
        return
    total_price = train['price'] * seat_count
    if input("总价为{}元，确认购买？(y/n)".format(total_price)) != 'y':
        print("取消购买！")
        return
    for i in range(seat_count):
        order = {'train_id': train_id, 'start': train['start'], 'end': train['end'], 'price': train['price']}
        user['orders'].append(order)
        trains[train_id]['seats'] -= 1
    print("购买成功！")


# 改签函数
def change_ticket(user):
    order_id = int(input("请输入要改签的订单号："))
    if order_id < 0 or order_id >= len(user['orders']):
        print("输入错误！")
        return
    order = user['orders'][order_id]
    new_train_id = input("请输入新的车次：")
    if new_train_id not in trains:
        print("输入错误！")
        return
    new_train = trains[new_train_id]
    if new_train['start'] != order['start'] or new_train['end'] != order['end']:
        print("新车次无法到达目的地！")
        return
    if new_train['seats'] == 0:
        print("新车次无余票！")
        return
    if input("确认改签？(y/n)") != 'y':
        print("取消改签！")
        return
    order['train_id'] = new_train_id
    order['price'] = new_train['price']
    trains[new_train_id]['seats'] -= 1
    trains[order['train_id']]['seats'] += 1
    print("改签成功！")


# 退票函数
def refund_ticket(user):
    order_id = int(input("请输入要退票的订单号："))
    if order_id < 0 or order_id >= len(user['orders']):
        print("输入错误！")
        return
    order = user['orders'][order_id]
    if input("确认退票？(y/n)") != 'y':
        print("取消退票！")
        return
    user['orders'].pop(order_id)
    trains[order['train_id']]['seats'] += 1
    print("退票成功！")


# 主程序
while True:
    print("欢迎使用火车售票系统！")
    print("1. 注册 2. 浏览 3. 购买 4. 改签 5. 退票 6. 退出")
    choice = input("请选择操作：")
    if choice == '1':
        register()
    elif choice == '2':
        show_trains()
    elif choice == '3':
        id_card = input("请输入身份证号：")
        user = None
        for u in users:
            if u['id_card'] == id_card:
                user = u
                break
        if user is None:
            print("用户不存在！")
            continue
        buy_ticket(user)
    elif choice == '4':
        id_card = input("请输入身份证号：")
        user = None
        for u in users:
            if u['id_card'] == id_card:
                user = u
                break
        if user is None:
            print("用户不存在！")
            continue
        change_ticket(user)
    elif choice == '5':
        id_card = input("请输入身份证号：")
        user = None
        for u in users:
            if u['id_card'] == id_card:
                user = u
                break
        if user is None:
            print("用户不存在！")
            continue
        refund_ticket(user)
    elif choice == '6':
        print("谢谢使用！")
        break
    else:
        print("输入错误！")

这个火车售票系统是用 Python 实现的，采用了字典来存储车辆信息和用户信息，实现了注册、浏览、购买、改签和退票等功能，可以显示多个车次每个车次要有不同的座位，不同的价格，可以一次性购买多张票，有余票限制，车次时间，和起点站，终点站，购买完成之后会显示订单。