程序功能主要分为3个部分，分别是对OPT、FIFO、LRU三种页面置换算法的实现。要求3部分的设计应该尽可能使用近似的实现方法。-procedures main function is divided into three parts, namely the OPT, FIFO, three pages replacement LRU algorithm implementation. Part of the three requirements should be designed as fa