JavaAlgorithms/DataStructures/Lists/SinglyLinkedList.java
2019-05-29 16:53:42 +05:30

182 lines
4.1 KiB
Java

/**
* 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;
}
}