AbstractClasses_Polymorphism.cpp

#include <iostream>
#include <vector>
#include <map>
#include <string>
#include <algorithm>
#include <set>
#include <cassert>
using namespace std;

struct Node{
   Node* next;
   Node* prev;
   int value;
   int key;
   Node(Node* p, Node* n, int k, int val):prev(p),next(n),key(k),value(val){};
   Node(int k, int val):prev(NULL),next(NULL),key(k),value(val){};
};

class Cache{
   
   protected: 
   map<int,Node*> mp; //map the key to the node in the linked list
   int cp;  //capacity
   Node* tail; // double linked list tail pointer
   Node* head; // double linked list head pointer
   virtual void set(int, int) = 0; //set function
   virtual int get(int) = 0; //get function

};

class LRUCache : Cache{
private :
    std::map<int,int> maap;
    int currentCapacity = 0;
public:
    LRUCache(int capacity = 0){
        cp = capacity;
    }
    void set(int key, int value){
        if(currentCapacity < cp){
            auto it = maap.find(key);
            if(it != maap.end()){
                it->second += 1;
            }
            else{
                maap.insert({key,value});
                currentCapacity+=1;   
            }
        }
        else{
            std::map<int,int>::iterator min; 
            int mn = 9999;
            
        for( std::map<int,int>::iterator it = maap . begin() ; it != maap.end() ; it ++){
            if(it->second < mn){
                min = it;
                mn  = it->second; 
            }
        }
            maap.erase(min);
            maap.insert({key,value});
        }
    }
    int get(int key){
        auto it = maap.find(key);
        return (it != maap.end()) ? it->second : -1;
    }
    ~LRUCache(){}
};

int main() {
   int n, capacity,i;
   cin >> n >> capacity;
   LRUCache l(capacity);
   for(i=0;i<n;i++) {
      string command;
      cin >> command;
      if(command == "get") {
         int key;
         cin >> key;
         cout << l.get(key) << endl;
      } 
      else if(command == "set") {
         int key, value;
         cin >> key >> value;
         l.set(key,value);
      }
   }
   return 0;
}