随机给出一个页面执行序列，如：1,5,3,4,2,1,3,4,5,7,9,……。要求计算以下几种置换算法的缺页数、缺页率和命中率。

  最佳置换算法OPT（Optimal）

  先进先出算法FIFO（First In First Out）

 最近最少使用算法LRU（Least Recently Used）-Random page gives an execution sequence, such as: 1,5,3,4,2,1,3,4,5,7,9, ....... Require replacement algorithm for computing several missing pages, missing pages rate and hit rate.

 　optimal replacement algorithm OPT (Optimal)

 　FIFO algorithm FIFO (First In First Out)

　least recently used algorithm LRU (Least Recently Used)