Circular Linked Lists

Circular Linked Lists

Author: careermonk

bin/chapter3linkedlists/CLLNode.class

@@ -0,0 +1,57 @@
+/*Copyright (c) Dec 21, 2014 CareerMonk Publications and others.
+ * E-Mail           	: [email protected] 
+ * Creation Date    	: 2015-01-10 06:15:46 
+ * Last modification	: 2006-05-31 
+               by		: Narasimha Karumanchi 
+ * File Name			: CLLNode.java
+ * Book Title			: Data Structures And Algorithms Made In Java
+ * Warranty         	: This software is provided "as is" without any 
+ * 							warranty; without even the implied warranty of 
+ * 							merchantability or fitness for a particular purpose. 
+ * 
+ */
+
+
+package chapter3linkedlists;
+
+public class CLLNode {
+	public CLLNode next;
+	public int data;
+
+	// Creates an empty node.
+	public CLLNode(){
+		next = null;
+		data = Integer.MIN_VALUE;
+	}
+
+	// Creates a node storing the specified data.
+	public CLLNode (int data){
+		next = null;
+		this.data = data;
+	}
+
+	// Returns the node that follows this one.
+	public CLLNode getNext(){
+		return next;
+	}
+
+	// Sets the node that follows this one.
+	public void setNext (CLLNode node){
+		next = node;
+	}
+
+	// Returns the data stored in this node.
+	public int getData(){
+		return data;
+	}
+
+	// Sets the data stored in this node.
+	public void setData (int elem){
+		data = elem;
+	}
+	
+	// Sets the data stored in this node.
+	public String toString (){
+		return Integer.toString(data);
+	}	
+}

bin/chapter3linkedlists/CircularLinkedList.class

@@ -0,0 +1,169 @@
+/*Copyright (c) Dec 21, 2014 CareerMonk Publications and others.
+ * E-Mail           	: [email protected] 
+ * Creation Date    	: 2015-01-10 06:15:46 
+ * Last modification	: 2006-05-31 
+               by		: Narasimha Karumanchi 
+ * File Name			: CircularLinkedList.java
+ * Book Title			: Data Structures And Algorithms Made In Java
+ * Warranty         	: This software is provided "as is" without any 
+ * 							warranty; without even the implied warranty of 
+ * 							merchantability or fitness for a particular purpose. 
+ * 
+ */
+
+
+package chapter3linkedlists;
+
+public class CircularLinkedList{
+	protected CLLNode tail;
+	protected int length;
+	
+	// Constructs a new circular list
+	public CircularLinkedList(){
+		tail = null;
+		length = 0;
+	}
+	
+	// Adds data to beginning of list.
+	public void add(int data){
+		addToHead(data);
+	}
+	
+	// Adds element to head of list
+	public void addToHead(int data){
+		CLLNode temp = new CLLNode(data);
+		if (tail == null) { // first data added
+		    tail = temp;
+		    tail.setNext(tail);
+		} else { // element exists in list
+		    temp.setNext(tail.getNext());
+		    tail.setNext(temp);
+		}
+		length++;
+	}
+	
+	// Adds element to tail of list
+	public void addToTail(int data){
+		// new entry:
+		addToHead(data);
+		tail = tail.getNext();
+	}
+	
+	// Returns data at head of list
+	public int peek(){
+		return tail.getNext().getData();
+	}
+	
+	// Returns data at tail of list
+	public int tailPeek(){
+		return tail.getData();
+	}
+	
+	// Returns and removes data from head of list
+	public int removeFromHead(){
+		CLLNode temp = tail.getNext(); // ie. the head of the list
+		if (tail == tail.getNext()) {
+			tail = null;
+		} else {
+			tail.setNext(temp.getNext());
+			temp.setNext(null); // helps clean things up; temp is free
+		}
+		length--;
+		return temp.getData();
+	}
+	
+	// Returns and removes data from tail of list
+	public int removeFromTail(){
+		if (isEmpty()){
+			return Integer.MIN_VALUE;
+		}
+		CLLNode finger = tail;
+		while (finger.getNext() != tail) {
+			finger = finger.getNext();
+		}
+		// finger now points to second-to-last data
+		CLLNode temp = tail;
+		if (finger == tail)	{
+			tail = null;
+		} else {
+			finger.setNext(tail.getNext());
+			tail = finger;
+		}
+		length--;
+		return temp.getData();
+	}
+	
+	// Returns true if list contains data, else false
+	public boolean contains(int data){
+		if (tail == null) return false;
+		CLLNode finger;
+		finger = tail.getNext();
+		while (finger != tail && (!(finger.getData() == data))){
+			finger = finger.getNext();
+		}
+		return finger.getData() == data;
+	}
+	
+	// Removes and returns element equal to data, or null
+	public int remove(int data){
+		if (tail == null) return Integer.MIN_VALUE;
+		CLLNode finger = tail.getNext();
+		CLLNode previous = tail;
+		int compares;
+		for (compares = 0; compares < length && (!(finger.getData() == data)); compares++) {
+			previous = finger;
+			finger = finger.getNext();
+		}
+		if (finger.getData() == data) {
+			// an example of the pigeon-hole principle
+			if (tail == tail.getNext()) { 
+				tail = null; }
+			else {
+				if (finger == tail) 
+					tail = previous;
+				previous.setNext(previous.getNext().getNext());
+			}
+			// finger data free
+			finger.setNext(null); 	// to keep things disconnected
+			length--;            	// fewer elements
+			return finger.getData();
+		}
+		else return Integer.MIN_VALUE;
+	}
+
+	// Return the current length of the CLL.
+	public int size(){
+		return length;
+	}
+    
+    	// Return the current length of the CLL.
+	public int length() {
+		return length;
+	}
+	
+	// Returns true if no elements in list
+	public boolean isEmpty(){
+		return tail == null;
+	}
+	
+	// Remove everything from the CLL.
+	public void clear(){
+		length = 0;
+		tail = null;
+	}
+
+	// Return a string representation of this collection, in the form: ["str1","str2",...].    
+	public String toString(){
+		String result = "[";
+		if (tail == null) {
+			return result+"]";
+		}
+		result = result + tail.getData();
+		CLLNode temp = tail.getNext();
+		while (temp != tail) {
+			result = result + "," + temp.getData();
+			temp = temp.getNext();
+		}
+		return result + "]";
+	}
+}

bin/chapter3linkedlists/LinkedList.class

@@ -151,7 +151,6 @@ public void remove(int position) {
 		if (position == 0) {
 			head = head.getNext();
 		}
-
 		// else advance to the correct position and remove
 		else {
 			ListNode temp = head;