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Create OS Page Replacement Algorithms in C++ tarunsinghofficial#2645
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OS Page Replacement Algorithms in C++ tarunsinghofficial#2645

1.FIFO (First-In-First-Out) Page Replacement Algorithm in C++
2.LRU (Least Recently Used) Page Replacement Algorithm in C++
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Abdullahkhanspn authored Oct 1, 2023
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OS Page Replacement Algorithms in C++ #2645

1.FIFO (First-In-First-Out) Page Replacement Algorithm in C++
#include <iostream>
#include <queue>
#include <unordered_set>

using namespace std;

class FIFOPageReplacement {
public:
FIFOPageReplacement(int capacity) {
this->capacity = capacity;
}

void referencePage(int page) {
if (pageTable.find(page) == pageTable.end()) {
if (pageQueue.size() == capacity) {
int removedPage = pageQueue.front();
pageQueue.pop();
pageTable.erase(removedPage);
}
pageQueue.push(page);
pageTable.insert(page);
}
}

void printPageTable() {
cout << "Page Table: ";
while (!pageQueue.empty()) {
cout << pageQueue.front() << " ";
pageQueue.pop();
}
cout << endl;
}

private:
int capacity;
queue<int> pageQueue;
unordered_set<int> pageTable;
};

int main() {
int capacity = 3; // Set the capacity of the page table
FIFOPageReplacement fifo(capacity);

int pages[] = {1, 2, 3, 4, 1, 2, 5};
int n = sizeof(pages) / sizeof(pages[0]);

for (int i = 0; i < n; i++) {
fifo.referencePage(pages[i]);
fifo.printPageTable();
}

return 0;
}

2.LRU (Least Recently Used) Page Replacement Algorithm in C++
#include <iostream>
#include <list>
#include <unordered_map>

using namespace std;

class LRUCache {
public:
LRUCache(int capacity) {
this->capacity = capacity;
}

int get(int key) {
if (cacheMap.find(key) != cacheMap.end()) {
// Move the accessed item to the front
cacheList.splice(cacheList.begin(), cacheList, cacheMap[key]);
return cacheMap[key]->second;
}
return -1;
}

void put(int key, int value) {
if (cacheMap.find(key) != cacheMap.end()) {
// If the key exists, update its value and move it to the front
cacheMap[key]->second = value;
cacheList.splice(cacheList.begin(), cacheList, cacheMap[key]);
} else {
// If the cache is full, remove the least recently used item
if (cacheList.size() >= capacity) {
int removedKey = cacheList.back().first;
cacheMap.erase(removedKey);
cacheList.pop_back();
}
// Add the new item to the front
cacheList.push_front({key, value});
cacheMap[key] = cacheList.begin();
}
}

void printCache() {
cout << "LRU Cache: ";
for (auto &entry : cacheList) {
cout << "(" << entry.first << "," << entry.second << ") ";
}
cout << endl;
}

private:
int capacity;
list<pair<int, int>> cacheList; // List of key-value pairs
unordered_map<int, list<pair<int, int>>::iterator> cacheMap; // Map for quick access to list iterator
};

int main() {
int capacity = 3; // Set the capacity of the LRU cache
LRUCache lru(capacity);

lru.put(1, 1);
lru.printCache();
lru.put(2, 2);
lru.printCache();
cout << "Get 1: " << lru.get(1) << endl; // Should print 1
lru.printCache();
lru.put(3, 3);
lru.printCache();
cout << "Get 2: " << lru.get(2) << endl; // Should print 2
lru.printCache();
lru.put(4, 4);
lru.printCache();
cout << "Get 1: " << lru.get(1) << endl; // Should print 1
lru.printCache();

return 0;
}

PLease Merge My Pr.

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