add singly linked list

Signed-off-by: Mattias Andrée <maandree@operamail.com>

1 files changed, 160 insertions, 0 deletions

diff --git a/src/datastructures/linkedlists/SinglyLinkedList.java b/src/datastructures/linkedlists/SinglyLinkedList.java
new file mode 100644
index 0000000..137736c
--- /dev/null
+++ b/src/datastructures/linkedlists/SinglyLinkedList.java
@@ -0,0 +1,160 @@
+/**
+ * Copyright © 2014  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package datastructures.linkedlists;
+
+
+/**
+ * Singly linked list class. A linked list is a
+ * list constructed from nodes, which hold stored
+ * values, with references to each other, this is
+ * usally an ineffective data structure, especially
+ * on high-level object orientated languages. A
+ * singly linked list only stores nodes with
+ * references to the following node. It also stores
+ * two refence nodes, the first node in the list,
+ * and the last node in the list. The implemention
+ * only implements methods that do not require
+ * iterating over all nodes for find a specific;
+ * all other methods' — those that are implemented
+ * — time complexity is Θ(1).
+ * 
+ * @param  <T>  The value stored in the structure
+ */
+public class SinglyLinkedList<T>
+{
+    /**
+     * Node for the list
+     */
+    public class Node
+    {
+	/**
+	 * Constructor
+	 * 
+	 * @param  value  The value to store in the list
+	 */
+	private Node(T value)
+	{
+	    this.value = value;
+	}
+	
+	
+	
+	/**
+	 * The value stored in the list by this node
+	 */
+	public T value;
+	
+	/**
+	 * The next node in the list
+	 */
+	public Node next = null;
+	
+    }
+    
+    
+    
+    /**
+     * The first node in the list
+     */
+    public Node head = null;
+    
+    /**
+     * The last node in the list
+     */
+    public Node tail = null;
+    
+    
+    
+    /**
+     * Insert a value in the beginning of the list
+     * 
+     * @param   value  The value to insert
+     * @return         The node that has be created and inserted
+     */
+    public Node insertBeginning(T value)
+    {
+	Node node = new Node(value);
+	node.next = this.head;
+	if (this.head == null)
+	    this.tail = node;
+	this.head = node;
+	return node;
+    }
+    
+    /**
+     * Remove the node at the beginning of the list
+     * 
+     * @return  The node that has been removed
+     */
+    public Node removeBeginning()
+    {
+	Node node = head;
+	if (node != null)
+	    head = head.next;
+	if (this.tail == node)
+	    this.tail = null;
+	return node;
+    }
+    
+    /**
+     * Insert a value after a specified, reference, node
+     * 
+     * @param   value        The value to insert
+     * @param   predecessor  The reference node
+     * @return               The node that has be created and inserted
+     */
+    public Node insertAfter(T value, Node predecessor)
+    {
+	Node node = new Node(value);
+	node.next = predecessor.next;
+	predecessor.next = node;
+	if (this.tail == predecessor)
+	    this.tail = node;
+	return node;
+    }
+    
+    /**
+     * Remove the node after a specified, reference, node
+     * 
+     * @param   predecessor  The reference node
+     * @return               The node that has been removed
+     */
+    public Node removeAfter(Node predecessor)
+    {
+	Node node = predecessor.next;
+	if (node == null)
+	    predecessor.next = node.next;
+	if (this.tail == node)
+	    this.tail = predecessor;
+	return node;
+    }
+    
+    /**
+     * Insert a value in the end of the list
+     * 
+     * @param   value  The value to insert
+     * @return         The node that has be created and inserted
+     */
+    public Node insertEnd(T value)
+    {
+	if (this.tail == null)
+	    return insertBeginning(value);
+	return insertAfter(value, this.tail);
+    }
+    
+}
+