/**

* This class implements a SinglyLinked List. This is done

* using SinglyLinkedList class and a LinkForLinkedList Class.

* <p>

* A linked list is similar to an array, it hold values.

* However, links in a linked list do not have indexes. With

* a linked list you do not need to predetermine it's size as

* it grows and shrinks as it is edited. This is an example of

* a singly linked list. Elements can only be added/removed

* at the head/front of the list.

*

* @author yanglbme

*/

class SinglyLinkedList {

/**

* Head refer to the front of the list

*/

private Node head;

/**

* This method inserts an element at the head

*

* @param x Element to be added

*/

public void insertHead(int x) {

Node newNode = new Node(x);

newNode.next = head;

head = newNode;

}

/**

* Inserts a new node at a specified position

*

* @param data data to be stored in a new node

* @param position position at which a new node is to be inserted

*/

public void insertNth(int data, int position) {

if (position < 0 || position > getSize()) {

throw new RuntimeException("position less than zero or position more than the count of list");

}

else if (position == 0)

insertHead(data);

else {

Node cur = head;

Node node = new Node(data);

for (int i = 1; i < position; ++i) {

cur = cur.next;

}

node.next = cur.next;

cur.next = node;

}

}

/**

* This method deletes an element at the head

*

* @return The element deleted

*/

public void deleteHead() {

if (isEmpty()) {

throw new RuntimeException("The list is empty!");

}

head = head.next;

}

/**

* This method deletes an element at Nth position

*/

public void deleteNth(int position) {

if (position < 0 || position > getSize()) {

throw new RuntimeException("position less than zero or position more than the count of list");

}

else if (position == 0)

deleteHead();

else {

Node cur = head;

for (int i = 1; i < position; ++i) {

cur = cur.next;

}

cur.next = cur.next.next;

}

}

/**

* Checks if the list is empty

*

* @return true is list is empty

*/

public boolean isEmpty() {

return getSize() == 0;

}

/**

* Prints contents of the list

*/

public void display() {

Node current = head;

while (current != null) {

System.out.print(current.value + " ");

current = current.next;

}

System.out.println();

}

/**

* Returns the size of the linked list

*/

public int getSize() {

if (head == null)

return 0;

else {

Node current = head;

int size = 1;

while (current.next != null) {

current = current.next;

size++;

}

return size;

}

}

/**

* Main method

*

* @param args Command line arguments

*/

public static void main(String args[]) {

SinglyLinkedList myList = new SinglyLinkedList();

assert myList.isEmpty();

myList.insertHead(5);

myList.insertHead(7);

myList.insertHead(10);

myList.display(); // 10 -> 7 -> 5

myList.deleteHead();

myList.display(); // 7 -> 5

myList.insertNth(11, 2);

myList.display(); // 7 -> 5 -> 11

myList.deleteNth(1);

myList.display(); // 7-> 11

}

}

/**

* This class is the nodes of the SinglyLinked List.

* They consist of a value and a pointer to the node

* after them.

*

* @author yanglbme

*/

class Node {

/**

* The value of the node

*/

int value;

/**

* Point to the next node

*/

Node next;

/**

* Constructor

*

* @param value Value to be put in the node

*/

Node(int value) {

this.value = value;

this.next = null;

}

}