please add these methods to the code below:

import java.util.Iterator; public class SkipList> { static final int PossibleLevels = 33; static class Entry { E element; Entry[] next; Entry prev; public Entry(E x, int lev) { element = x; next = new Entry[lev]; // add more code as needed } public E getElement() { return element; } } // Constructor public SkipList() { } // Add x to list. If x already exists, reject it. Returns true if new node is added to list public boolean add(T x) { return true; } // Find smallest element that is greater or equal to x public T ceiling(T x) { return null; } // Does list contain x? public boolean contains(T x) { return false; } // Return first element of list public T first() { return null; } // Find largest element that is less than or equal to x public T floor(T x) { return null; } // Return element at index n of list. First element is at index 0. public T get(int n) { return null; } // Is the list empty? public boolean isEmpty() { return false; } // Iterate through the elements of list in sorted order public Iterator iterator() { return null; } // Return last element of list public T last() { return null; } // Remove x from list. Removed element is returned. Return null if x not in list public T remove(T x) { return null; } // Return the number of elements in the list public int size() { return 0; } }

Driver is Provided:

import java.io.File; import java.io.FileNotFoundException; import java.util.Iterator; import java.util.Scanner; //Driver program for skip list implementation. public class SkipListDriver { public static void main(String[] args) throws FileNotFoundException { Scanner sc; if (args.length > 0) { File file = new File(args[0]); sc = new Scanner(file); } else { sc = new Scanner(System.in); } String operation = ""; long operand = 0; long result = 0; Long returnValue = null; SkipList skipList = new SkipList(); // Initialize the timer Timer timer = new Timer(); while (!((operation = sc.next()).equals("End"))) { returnValue = null; switch (operation) { case "Add": operand = sc.nextLong(); if(skipList.add(operand)) { returnValue = 1L; } break; case "Ceiling": operand = sc.nextLong(); returnValue = skipList.ceiling(operand); break; case "First": returnValue = skipList.first(); break; case "Get": int intOperand = sc.nextInt(); returnValue = skipList.get(intOperand); break; case "Last": returnValue = skipList.last(); break; case "Floor": operand = sc.nextLong(); returnValue = skipList.floor(operand); break; case "Remove": operand = sc.nextLong(); if (skipList.remove(operand) != null) { returnValue = 1L; } break; case "Contains": operand = sc.nextLong(); if (skipList.contains(operand)) { returnValue = 1L; } break; } if (returnValue != null) { result += returnValue; } } // End Time timer.end(); System.out.println(result); System.out.println(timer); } /** Timer class for roughly calculating running time of programs * @author rbk * Usage: Timer timer = new Timer(); * timer.start(); * timer.end(); * System.out.println(timer); // output statistics */ public static class Timer { long startTime, endTime, elapsedTime, memAvailable, memUsed; public Timer() { startTime = System.currentTimeMillis(); } public void start() { startTime = System.currentTimeMillis(); } public Timer end() { endTime = System.currentTimeMillis(); elapsedTime = endTime-startTime; memAvailable = Runtime.getRuntime().totalMemory(); memUsed = memAvailable - Runtime.getRuntime().freeMemory(); return this; } public String toString() { return "Time: " + elapsedTime + " msec. " + "Memory: " + (memUsed/1048576) + " MB / " + (memAvailable/1048576) + " MB."; } } }

* add(x): Add a new element x to the list. If x already exists in the skip list, replace it and return false. otherwise, insert x into the skip list and return true. ceiling(x): Find smallest element that is greater or equal to x. contains (x): Does list contain x? first): Return st. first element of 1 * add(x): Add a new element x to the list. If x already exists in the skip list, replace it and return false. otherwise, insert x into the skip list and return true. ceiling(x): Find smallest element that is greater or equal to x. contains (x): Does list contain x? first): Return st. first element of 1