Using linked list implementation for generic stack class. The code for linked li
ID: 3803292 • Letter: U
Question
Using linked list implementation for generic stack class. The code for linked list version of generic stack (LinkedStack< E >) and generic node (Node< E >) classes is provided:
LinkedStack.java
Node.java
You should not make any changes to these classes (Node class and LinkedStack class).
1: Write a program (with the name Palindrome.java) that will use stacks to recognize palindromic sequences of integers. A sequence of integers is palindromic if it reads the same backward and forward. For example, sequence 5 12 32 4 32 12 5 is palindromic. Sequence 3 4 5 4 2 3 is not palindromic. Your program should prompt the user to enter a sequence of integers in a line and output whether the sequence is palindromic or not. Dialog with the user may look like the following:
You will need three stacks to implement the program. You may only use stacks to store the numbers. You are not allowed to store numbers in an array.
********************************
// File: Node.java from the package edu.colorado.nodes
// Complete documentation is available from the Node link in:
// http://www.cs.colorado.edu/~main/docs
// package edu.colorado.nodes;
/******************************************************************************
* A Node<E> provides a generic node for a linked list. Each node
* contains a piece of data (which is a reference to an E object) and a link
* (which is a reference to the next node of the list). The reference stored
* in a node can be null.
*
* @note
* Lists of nodes can be made of any length, limited only by the amount of
* free memory in the heap. But beyond Integer.MAX_VALUE (2,147,483,647),
* the answer from listLength is incorrect because of arithmetic
* overflow.
* @see
* <A href="../../../../edu/colorado/nodes/Node.java">
* Java Source Code for this class
* (www.cs.colorado.edu/~main/edu/colorado/nodes/Node.java) </A>
*
* @author Michael Main
* <A href="mailto:main@colorado.edu"> (main@colorado.edu) </A>
*
* @version
* Jul 17, 2005
*
* @see BooleanNode
* @see ByteNode
* @see CharNode
* @see DoubleNode
* @see FloatNode
* @see IntNode
* @see LongNode
* @see ShortNode
******************************************************************************/
public class Node<E>
{
// Invariant of the Node class:
// 1. Each node has one reference to an E Object, stored in the instance
// variable data.
// 2. For the final node of a list, the link part is null.
// Otherwise, the link part is a reference to the
// next node of the list.
private E data;
private Node<E> link;
/**
* Initialize a node with a specified initial data and link to the next
* node. Note that the initialLink may be the null reference,
* which indicates that the new node has nothing after it.
* @param initialData
* the initial data of this new node
* @param initialLink
* a reference to the node after this new node--this reference may be null
* to indicate that there is no node after this new node.
* @postcondition
* This node contains the specified data and link to the next node.
**/
public Node(E initialData, Node<E> initialLink)
{
data = initialData;
link = initialLink;
}
/**
* Modification method to add a new node after this node.
* @param element
* the data to place in the new node
* @postcondition
* A new node has been created and placed after this node.
* The data for the new node is element. Any other nodes
* that used to be after this node are now after the new node.
* @exception OutOfMemoryError
* Indicates that there is insufficient memory for a new
* Node.
**/
public void addNodeAfter(E element)
{
link = new Node<E>(element, link);
}
/**
* Accessor method to get the data from this node.
* @param - none
* @return
* the data from this node
**/
public E getData( )
{
return data;
}
/**
* Accessor method to get a reference to the next node after this node.
* @param - none
* @return
* a reference to the node after this node (or the null reference if there
* is nothing after this node)
**/
public Node<E> getLink( )
{
return link;
}
/**
* Copy a list.
* @param source
* the head of a linked list that will be copied (which may be
* an empty list in where source is null)
* @return
* The method has made a copy of the linked list starting at
* source. The return value is the head reference for the
* copy.
* @exception OutOfMemoryError
* Indicates that there is insufficient memory for the new list.
**/
public static <E> Node<E> listCopy(Node<E> source)
{
Node<E> copyHead;
Node<E> copyTail;
// Handle the special case of the empty list.
if (source == null)
return null;
// Make the first node for the newly created list.
copyHead = new Node<E>(source.data, null);
copyTail = copyHead;
// Make the rest of the nodes for the newly created list.
while (source.link != null)
{
source = source.link;
copyTail.addNodeAfter(source.data);
copyTail = copyTail.link;
}
// Return the head reference for the new list.
return copyHead;
}
/**
* Copy a list, returning both a head and tail reference for the copy.
* @param source
* the head of a linked list that will be copied (which may be
* an empty list in where source is null)
* @return
* The method has made a copy of the linked list starting at
* source. The return value is an
* array where the [0] element is a head reference for the copy and the [1]
* element is a tail reference for the copy.
* @exception OutOfMemoryError
* Indicates that there is insufficient memory for the new list.
**/
public static <E> Node<E>[ ] listCopyWithTail(Node<E> source)
{
Node<E> copyHead;
Node<E> copyTail;
Node<E>[ ] answer = (Node<E>[]) new Object[2];
// Handle the special case of the empty list.
if (source == null)
return answer; // The answer has two null references .
// Make the first node for the newly created list.
copyHead = new Node<E>(source.data, null);
copyTail = copyHead;
// Make the rest of the nodes for the newly created list.
while (source.link != null)
{
source = source.link;
copyTail.addNodeAfter(source.data);
copyTail = copyTail.link;
}
// Return the head and tail references.
answer[0] = copyHead;
answer[1] = copyTail;
return answer;
}
/**
* Compute the number of nodes in a linked list.
* @param head
* the head reference for a linked list (which may be an empty list
* with a null head)
* @return
* the number of nodes in the list with the given head
* @note
* A wrong answer occurs for lists longer than Int.MAX_VALUE.
**/
public static <E> int listLength(Node<E> head)
{
Node<E> cursor;
int answer;
answer = 0;
for (cursor = head; cursor != null; cursor = cursor.link)
answer++;
return answer;
}
/**
* Copy part of a list, providing a head and tail reference for the new copy.
* @param start/end
* references to two nodes of a linked list
* @param copyHead/copyTail
* the method sets these to refer to the head and tail node of the new
* list that is created
* @precondition
* start and end are non-null references to nodes
* on the same linked list,
* with the start node at or before the end node.
* @return
* The method has made a copy of the part of a linked list, from the
* specified start node to the specified end node. The return value is an
* array where the [0] component is a head reference for the copy and the
* [1] component is a tail reference for the copy.
* @exception IllegalArgumentException
* Indicates that start and end do not satisfy
* the precondition.
* @exception OutOfMemoryError
* Indicates that there is insufficient memory for the new list.
**/
public static <E> Node<E>[ ] listPart(Node<E> start, Node<E> end)
{
Node<E> copyHead;
Node<E> copyTail;
Node<E> cursor;
Node<E>[ ] answer = (Node<E>[]) new Object[2];
// Check for illegal null at start or end.
if (start == null)
throw new IllegalArgumentException("start is null");
if (end == null)
throw new IllegalArgumentException("end is null");
// Make the first node for the newly created list.
copyHead = new Node<E>(start.data, null);
copyTail = copyHead;
cursor = start;
// Make the rest of the nodes for the newly created list.
while (cursor != end)
{
cursor = cursor.link;
if (cursor == null)
throw new IllegalArgumentException
("end node was not found on the list");
copyTail.addNodeAfter(cursor.data);
copyTail = copyTail.link;
}
// Return the head and tail references
answer[0] = copyHead;
answer[1] = copyTail;
return answer;
}
/**
* Find a node at a specified position in a linked list.
* @param head
* the head reference for a linked list (which may be an empty list in
* which case the head is null)
* @param position
* a node number
* @precondition
* position > 0.
* @return
* The return value is a reference to the node at the specified position in
* the list. (The head node is position 1, the next node is position 2, and
* so on.) If there is no such position (because the list is too short),
* then the null reference is returned.
* @exception IllegalArgumentException
* Indicates that position is zero.
**/
public static <E> Node<E> listPosition(Node<E> head, int position)
{
Node<E> cursor;
int i;
if (position == 0)
throw new IllegalArgumentException("position is zero");
cursor = head;
for (i = 1; (i < position) && (cursor != null); i++)
cursor = cursor.link;
return cursor;
}
/**
* Search for a particular piece of data in a linked list.
* @param head
* the head reference for a linked list (which may be an empty list in
* which case the head is null)
* @param target
* a target to search for
* @return
* The return value is a reference to the first node that contains the
* specified target. If the target is non-null, then the
* target.equals method is used to find such a node.
* The target may also be null, in which case the return value is a
* reference to the first node that contains a null reference for its
* data. If there is no node that contains the target, then the null
* reference is returned.
**/
public static <E> Node<E> listSearch(Node<E> head, E target)
{
Node<E> cursor;
if (target == null)
{ // Search for a node in which the data is the null reference.
for (cursor = head; cursor != null; cursor = cursor.link)
if (cursor.data == null)
return cursor;
}
else
{ // Search for a node that contains the non-null target.
for (cursor = head; cursor != null; cursor = cursor.link)
if (target.equals(cursor.data))
return cursor;
}
return null;
}
/**
* Modification method to remove the node after this node.
* @param - none
* @precondition
* This node must not be the tail node of the list.
* @postcondition
* The node after this node has been removed from the linked list.
* If there were further nodes after that one, they are still
* present on the list.
* @exception NullPointerException
* Indicates that this was the tail node of the list, so there is nothing
* after it to remove.
**/
public void removeNodeAfter( )
{
link = link.link;
}
/**
* Modification method to set the data in this node.
* @param newData
* the new data to place in this node
* @postcondition
* The data of this node has been set to newData.
* This data is allowed to be null.
**/
public void setData(E newData)
{
data = newData;
}
/**
* Modification method to set the link to the next node after this node.
* @param newLink
* a reference to the node that should appear after this node in the linked
* list (or the null reference if there is no node after this node)
* @postcondition
* The link to the node after this node has been set to newLink.
* Any other node (that used to be in this link) is no longer connected to
* this node.
**/
public void setLink(Node<E> newLink)
{
link = newLink;
}
}
**************************
// File: LinkedStack.java from the package edu.colorado.collections
// Complete documentation is available from the LinkedStack link in:
// http://www.cs.colorado.edu/~main/docs/
// package edu.colorado.collections;
import java.util.EmptyStackException;
// import edu.colorado.nodes.Node;
/******************************************************************************
* A <CODE>LinkedStack<E></CODE> is a stack of references to
* <code>E</code>objects.
*
* <dl><dt><b>Limitations:</b><dd>
* Beyond <CODE>Int.MAX_VALUE</CODE> items, <CODE>size</CODE> is wrong.
* </dl>
*
* <dt><b>Java Source Code for this class:</b><dd>
* <A href="../../../../edu/colorado/collections/LinkedStack.java">
* http://www.cs.colorado.edu/~main/edu/colorado/collections/LinkedStack.java
* </A>
*
* @author Michael Main
* <A href="mailto:main@colorado.edu"> (main@colorado.edu) </A>
*
* @version
* Jul 21, 2005
*
* @see ArrayStack
******************************************************************************/
public class LinkedStack<E> implements Cloneable
{
// Invariant of the LinkedStack class:
// 1. The items in the stack are stored in a linked list, with the top of
// the stack stored at the head node, down to the bottom of the stack
// at the final node.
// 2. The instance variable top is the head reference of the linked list
// of items.
private Node<E> top;
/**
* Initialize an empty stack.
* @param - none
* <dt><b>Postcondition:</b><dd>
* This stack is empty.
**/
public LinkedStack( )
{
top = null;
}
/**
* Generate a copy of this stack.
* @param - none
* @return
* The return value is a copy of this stack. Subsequent changes to the
* copy will not affect the original, nor vice versa.
* @exception OutOfMemoryError
* Indicates insufficient memory for creating the clone.
**/
public LinkedStack<E> clone( )
{ // Clone a LinkedStack<E>.
LinkedStack<E> answer;
try
{
answer = (LinkedStack<E>) super.clone( );
}
catch (CloneNotSupportedException e)
{
// This exception should not occur. But if it does, it would probably indicate a
// programming error that made super.clone unavailable. The most comon error
// The most common error would be forgetting the "Implements Cloneable"
// clause at the start of this class.
throw new RuntimeException
("This class does not implement Cloneable");
}
// The generic listCopy method gets the type of E from top.
answer.top = Node.listCopy(top);
return answer;
}
/**
* Determine whether this stack is empty.
* @param - none
* @return
* <CODE>true</CODE> if this stack is empty;
* <CODE>false</CODE> otherwise.
**/
public boolean isEmpty( )
{
return (top == null);
}
/**
* Get the top item of this stack, without removing the item.
* @param - none
* <dt><b>Precondition:</b><dd>
* This stack is not empty.
* @return
* the top item of the stack
* @exception EmptyStackException
* Indicates that this stack is empty.
**/
public E peek( )
{
if (top == null)
// EmptyStackException is from java.util and its constructor has no argument.
throw new EmptyStackException( );
return top.getData( );
}
/**
* Get the top item, removing it from this stack.
* @param - none
* <dt><b>Precondition:</b><dd>
* This stack is not empty.
* <dt><b>Postcondition:</b><dd>
* The return value is the top item of this stack, and the item has
* been removed.
* @exception EmptyStackException
* Indicates that this stack is empty.
**/
public E pop( )
{
E answer;
if (top == null)
// EmptyStackException is from java.util and its constructor has no argument.
throw new EmptyStackException( );
answer = top.getData( );
top = top.getLink( );
return answer;
}
/**
* Push a new item onto this stack. The new item may be the null
* reference.
* @param <CODE>item</CODE>
* the item to be pushed onto this stack
* <dt><b>Postcondition:</b><dd>
* The item has been pushed onto this stack.
* @exception OutOfMemoryError
* Indicates insufficient memory for increasing the stack's capacity.
**/
public void push(E item)
{
top = new Node<E>(item, top);
}
/**
* Accessor method to determine the number of items in this stack.
* @param - none
* @return
* the number of items in this stack
**/
public int size( )
{
// The generic listLength method gets the type of E from top.
return Node.listLength(top);
}
/**
* Return a string representation of this stack. The string
* returned by this method will show the stack with top on the left
* and bottom on the right, elements separated by '|'
*
* @return a string representation of this stack.
**/
public String toString()
{
if (top != null)
{
String answer = "";
Node<E> current = top;
while (current != null)
{
answer = answer + current.getData() + "|";
current = current.getLink();
}
return answer;
}
else return "|";
}
}
Explanation / Answer
Here's how you can check (using stack) whether the given String is palindromic or not --
Palindrome.java (as requested in question)
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