public class ThreeTenDLList<T> implements Iterable<T> { // doubly linked list with both head and tail, no dummy nodes private Node<T> head; //beginning of list private Node<T> tail; //end of list // ADD MORE PRIVATE MEMBERS HERE IF NEEDED! //constructor // initialize the list to being an empty list public ThreeTenDLList(){ } // report number of items // O(1) public int size(){ //default return, remove or updated as needed return -1; } // returns the first value from the beginning of the list // do not remove the value! // return null if list is empty // O(1) public T getFirst() { //default return, remove or updated as needed return null; } // inserts a new node with value at the begining of the list // you can assume value is not null // O(1) public void addFirst(T value) { } // remove and return the first value in the list //return null if list is empty // O(1) public T removeFirst(){ //default return, remove or updated as needed return null; } // returns the last value from the end of the list // do not remove the value! // return null if list is empty // O(1) public T getLast() { //default return, remove or updated as needed return null; } // inserts a new value at the end of the list // you can assume value is not null // O(1) public void addLast(T value) { } // remove and return the last value from the end of the list //return null if list is empty // O(1) public T removeLast(){ //default return, remove or updated as needed return null; } //remove and return the first occurence of value // (i.e. the occurence that is closest to head) // - return null if value is not present // - note: must return the data from list, not the argument value //O(n) where n is the number of items public T remove(T value){ //default return, remove or updated as needed return null; } // return a string representing the values in the list starting from index to end, // seperated by a single space // return empty string for invalid start or empty list // O(n) where n is the number of items // Warning: concatenating String objects will yield a O(n^2) solution public String listToString(int start) { //default return, remove or updated as needed return null; } // return a string representing the values in the list, from end to beginning, // seperated by a single space // return empty string for an empty list // O(n) where n is the number of items // Warning: concatenating String objects will yield a O(n^2) solution public String listToStringBackward() { //default return, remove or updated as needed return null; } public Iterator<T> iterator() { //Return an iterator that traverses from //the beginning (head) to the end (tail) of the list //The iterator's hasNext() and next() methods //must both be O(1) //next() should throw a NullPointerException //if you try to use next when there are no //more items (any error message is fine). //update / replace this dummy return statement as neede.

1. public class ThreeTenDLList<T> implements Iterable<T> {
// doubly linked list with both head and tail, no dummy nodes
private Node<T> head; //beginning of list
private Node<T> tail; //end of list
// ADD MORE PRIVATE MEMBERS HERE IF NEEDED!
//constructor
// initialize the list to being an empty list
public ThreeTenDLList(){
}
// report number of items
// O(1)
public int size(){
//default return, remove or updated as needed
return -1;
}
// returns the first value from the beginning of the list
// do not remove the value!
// return null if list is empty
// O(1)
public T getFirst() {
//default return, remove or updated as needed
return null;
}
// inserts a new node with value at the begining of the list
// you can assume value is not null
// O(1)
public void addFirst(T value) {
}
// remove and return the first value in the list
//return null if list is empty
// O(1)
public T removeFirst(){
//default return, remove or updated as needed
return null;
}

2. // returns the last value from the end of the list
// do not remove the value!
// return null if list is empty
// O(1)
public T getLast() {
//default return, remove or updated as needed
return null;
}
// inserts a new value at the end of the list
// you can assume value is not null
// O(1)
public void addLast(T value) {
}
// remove and return the last value from the end of the list
//return null if list is empty
// O(1)
public T removeLast(){
//default return, remove or updated as needed
return null;
}
//remove and return the first occurence of value
// (i.e. the occurence that is closest to head)
// - return null if value is not present
// - note: must return the data from list, not the argument value
//O(n) where n is the number of items
public T remove(T value){
//default return, remove or updated as needed
return null;
}
// return a string representing the values in the list starting from index to end,
// seperated by a single space
// return empty string for invalid start or empty list
// O(n) where n is the number of items
// Warning: concatenating String objects will yield a O(n^2) solution
public String listToString(int start) {

3. //default return, remove or updated as needed
return null;
}
// return a string representing the values in the list, from end to beginning,
// seperated by a single space
// return empty string for an empty list
// O(n) where n is the number of items
// Warning: concatenating String objects will yield a O(n^2) solution
public String listToStringBackward() {
//default return, remove or updated as needed
return null;
}
public Iterator<T> iterator() {
//Return an iterator that traverses from
//the beginning (head) to the end (tail) of the list
//The iterator's hasNext() and next() methods
//must both be O(1)
//next() should throw a NullPointerException
//if you try to use next when there are no
//more items (any error message is fine).
//update / replace this dummy return statement as needed
return null;
}
public Iterator<T> backwardIterator() {
//Return an iterator that traverses from
//the end (tail) to the beginning (head) of the list
//The iterator's hasNext() and next() methods
//must both be O(1)
//next() should throw a NullPointerException
//if you try to use next when there are no
//more items (any error message is fine).
//update / replace this dummy return statement as needed
return null;

4. }