模拟实现磁盘调度算法：扫描（SCAN）算法和最短寻道时间优先算法（SSTF）。对给出的任意的磁盘请求序列、计算平均寻道长度。要求可定制磁盘请求序列长度、磁头起始位置、磁头移动方向。-Analog disk scheduling algorithm: scan (SCAN) algorithm and the shortest seek time first algorithm (SSTF). On any given disk request sequence, calculate the av