编程序实现下述磁盘调度算法,并求出每种算法的平均寻道长度，要求设计主界面以灵活选择某算法，且以下算法都要实现：

1、先来先服务算法（FCFS）

2、最短寻道时间优先算法（SSTF）

3、扫描算法（SCAN）

4、循环扫描算法（CSCAN）

-programmed to achieve the following disk-scheduling algorithms, and each algorithm calculated the average Seeking length, main interface designed in a flexible choice of a particular algorithm and the algorithm must achieve the following : 1. first-come first-service algorithm (FCFS queue) 2, the shortest tracking time priority algorithm (SSTF), 3 scanning algorithm (SCAN) 4, cycle scanning algorithm (rltrasonic)