模拟一个飞机票订票和退票系统 假定某民航机场有M个航次的班机，每个航次都只到达一个目的地。试为该机场售票处设计一个自动订票和退票系统。 要求系统具有下列功能： （1）订票。若该航次余票数大于等于乘客订票数，则在该航次的乘客表（按乘客姓氏字母顺序连接）中，插入订票乘客的信息项，并修改该航次有关数据，否则，给出相应的提示信息。 （2）退票。若该航次当前退票数小于等于乘客原订票数，则在相应的乘客表中找到该乘客项，修改该航次及乘客表中有关数据。当由于退票，使得该乘客的订票数为零时，要从乘客表中撤消该乘客项；否则，给出相应的提示信息。 （3）将某航次的余票数恢复初值——该航次的最大客票数。 当客户订票数要求不能满足时，系统也可想客户提供到达同一目的地的其他航线情况。-simulated a plane ticket booking system and refund the assumption that a civil airport M voyages flights, each voyage only reach a destination. Trial Design for the airport ticket booking and an automatic refund system. System requirements with the following functions : (a) booking. If the voyage I mean votes greater than the number of passengers booking, the passenger voyage (by passengers connecting in alphabetical order), insert the passenger booking information, and modify the voyage of the data, given the corresponding message. (2) Refund. If the voyage is less than the current refund equal to the number of passengers scheduled votes, the passengers in the corresponding table to find the passengers, to revise the voyage and the passengers of the data table. When the refund due, making