Page Faults in LRU

//{ Driver Code Starts
// Initial Template for C++



#include <bits/stdc++.h>
using namespace std;

// } Driver Code Ends
// User function Template for C++

class Solution{
private:
class Node
{
    public:
    int val;
    Node* next;
    Node* prev;
    Node(int v)
    {
        val=v;
        next=NULL;
        prev=NULL;
    }
};
public:
    Node *head = new Node(-1);
    Node *tail = new Node(-1);
    map<int, Node*> mp;
      int size;

    void addNode(Node *ptr) {
        ptr->prev = head;
        ptr->next = head->next;
        head->next->prev = ptr;
        head->next = ptr;

    }

    void deleteNode(Node *ptr) {
        Node *next_of_ptr = ptr->next;
        Node *prev_of_ptr = ptr->prev;

        prev_of_ptr->next = next_of_ptr;
        next_of_ptr->prev = prev_of_ptr;


    }
    bool GET(int key)
    {
        if(mp.find(key) != mp.end()) {
            Node* resnode = mp[key];
            mp.erase(key);
            deleteNode(resnode);


            addNode(resnode);
            mp[key] = head->next;

            return 1;
        }
        return 0;
    }

    void SET(int key, int value)
    {
        if(mp.find(key) != mp.end()) {
            Node* resnode = mp[key];
            deleteNode(resnode);
        }
        if(mp.size() == value) {
            mp.erase(tail->prev->val);
            deleteNode(tail->prev);
        }


        addNode(new Node(key));
        mp[key] = head->next;
    }
    int pageFaults(int N, int C, int pages[]){
        // code here
       head->next = tail;
       tail->prev = head;
       int ans=0;
       for(int i=0;i<N;i++)
       {
           if(GET(pages[i]))
           {
               continue;
           }
           else
           {
               ans++;
               SET(pages[i],C);
           }
       }
       return ans;
    }
};

//{ Driver Code Starts.

int main(){
    int t;
    cin>>t;
    while(t--){
        int N, C;
        cin>>N;
        int pages[N];
        for(int i = 0;i < N;i++)
            cin>>pages[i];
        cin>>C;

        Solution ob;
        cout<<ob.pageFaults(N, C, pages)<<"\n";
    }
    return 0;
}
// } Driver Code Ends