abstract-classes-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: public Cache {
    private:
        map<int,int> mymap;
        map<int,int>::iterator it;
        int capacity;
    public:
    LRUCache(int arg) {capacity = arg;}
    int get(int key){
        it = mymap.find(key);
        if(key > capacity || it == mymap.end()) return -1;
        else return it->second ;
    } 
    void set(int key, int val){
        mymap.erase(key);
        mymap.insert(pair <int,int> (key,val)); 
        if(mymap.size() > capacity){
            it = mymap.end();
            mymap.erase(it->first);
        }
    }
};

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;
}