请为以下代码加注释：#include <iostream> #include <list> #include <random> using namespace std; int main() { // Generate page access sequence using random function random_device rd; mt19937 gen(rd()); uniform_int_distribution<> dis(0, 18); list<int> page_access_sequence; for (int i = 0; i < 54; i++) { page_access_sequence.push_back(dis(gen)); } // LRU algorithm for page replacement int M = 6; // Number of main memory frames list<int> main_memory; int page_faults = 0; for (auto it = page_access_sequence.begin(); it != page_access_sequence.end(); ++it) { // Check if page is already in main memory auto pos = find(main_memory.begin(), main_memory.end(), *it); if (pos != main_memory.end()) { // Page hit, move page to front of list main_memory.erase(pos); main_memory.push_front(*it); } else { // Page fault, replace least recently used page page_faults++; if (main_memory.size() == M) { main_memory.pop_back(); } main_memory.push_front(*it); } } // Output page replacement sequence and page fault rate cout << "Page replacement sequence: "; for (auto it = main_memory.begin(); it != main_memory.end(); ++it) { cout << *it << " "; } cout << endl; cout << "Page fault rate: " << (double)page_faults / (double)54 << endl; return 0; }

// 引入需要的头文件
#include <iostream> // 标准输入输出流
#include <list> // 双向链表
#include <random> // 随机数生成器

using namespace std;

int main() {
// 使用随机函数生成页面访问序列
random_device rd; // 生成随机种子
mt19937 gen(rd()); // 随机数生成器
uniform_int_distribution<> dis(0, 18); // 生成0-18的均匀分布随机数
list<int> page_access_sequence; // 双向链表，存储页面访问序列
for (int i = 0; i < 54; i++) { // 生成54个随机数，存储在page_access_sequence中
page_access_sequence.push_back(dis(gen));
}

// LRU算法，用于页面置换
int M = 6; // 主存储器帧数
list<int> main_memory; // 双向链表，存储主存储器中的页面
int page_faults = 0; // 页面缺失次数
for (auto it = page_access_sequence.begin(); it != page_access_sequence.end(); ++it) { // 遍历页面访问序列
// 检查页面是否已经在主存储器中
auto pos = find(main_memory.begin(), main_memory.end(), *it); // 找到页面位置
if (pos != main_memory.end()) { // 页面已经在主存储器中
// 页面命中，将页面移到链表头部
main_memory.erase(pos); // 删除旧的页面
main_memory.push_front(*it); // 将页面移到链表头部
}
else { // 页面不在主存储器中，产生页面缺失
page_faults++; // 增加页面缺失次数
if (main_memory.size() == M) { // 主存储器已满，需要进行页面置换
main_memory.pop_back(); // 移除最久未访问的页面
}
main_memory.push_front(*it); // 将新页面加入主存储器
}
}

// 输出页面置换序列和页面缺失率
cout << "Page replacement sequence: ";
for (auto it = main_memory.begin(); it != main_memory.end(); ++it) { // 输出主存储器中的页面
cout << *it << " ";
}
cout << endl;
cout << "Page fault rate: " << (double)page_faults / (double)54 << endl;

return 0;
}