n th to last element, C#

n th to last element

//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace LinkedListAlgorithms
{
    partial class LinkedListStack
    {
        //Find nth to last element of a singly linked list implemented as a stack
        //1 returns the last object in the linked list
        public object FindNToLast(int x)
        {
            if (head == null)
                throw new Exception("Empty linked list");
            if (x < 1)
                throw new Exception("Index out of range");
 
            Node lag = head;
            Node lead = head;
 
            //Move the lead pointer up (x-1 positions) while leaving the lag pointer behind
            for (int i = 1; i < x; i++)
                lead = lead.Next;
 
            //Move the lag and lead pointers up one at a time until the lead is at the end of the list
            while (lead.Next != null)
            {
                lag = lag.Next;
                lead = lead.Next;
            }
            return lag.Data;
        }       
    }
}


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