Nthnodefromend.cpp

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

/* Link list Node */
struct Node {
  int data;
  struct Node *next;
  Node(int x) {
    data = x;
    next = NULL;
  }
};
int getNthFromLast(struct Node* head, int n);

/* struct Node {
  int data;
  struct Node *next;
  Node(int x) {
    data = x;
    next = NULL;
  }
};
*/

//Function to find the data of nth node from the end of a linked list.
class Solution{
public:
    int getNthFromLast(Node *head, int n)
    {
        Node *slow=head;
    Node *fast=head;
    for(int i=0;i<n;i++)
    {
         if(fast==NULL)
             return -1;
         fast=fast->next;
    }
    while(fast!=NULL)
    {
        slow=slow->next;
        fast=fast->next;
    }
    return slow->data;
    }
};


int main()
{
  int T,i,n,l,k;

    cin>>T;

    while(T--){
    struct Node *head = NULL,  *tail = NULL;

        cin>>n>>k;
        int firstdata;
        cin>>firstdata;
        head = new Node(firstdata);
        tail = head;
        for(i=1;i<n;i++)
        {
            cin>>l;
            tail->next = new Node(l);
            tail = tail->next;
        }
    Solution obj;
    cout<<obj.getNthFromLast(head, k)<<endl;
    }
    return 0;
}