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201 lines
4.1 KiB
201 lines
4.1 KiB
package net.jrtechs.www.DataStructures.Lists.LinkedList;
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import net.jrtechs.www.DataStructures.Lists.IList;
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import net.jrtechs.www.DataStructures.Node;
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/**
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* Implementation of a linked list.
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*
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* @author Jeffery Russell
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*/
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public class LinkedList<E> implements IList<E>
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{
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/** Head node */
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private Node<E> head;
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/**Stored to make insertions o(1) */
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private Node<E> tail;
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/** Keeps track of size so it doesn't
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* have to be re-calculated each time it's used */
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private int size;
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/**
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* Creates a new empty linked list
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*/
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public LinkedList()
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{
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this.head = null;
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this.tail = null;
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this.size = 0;
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}
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/**
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* Creates a new linked list with an
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* initial element stored inside of it
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*
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* @param o initial element
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*/
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public LinkedList(E o)
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{
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this.head = new Node<>(o);
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this.tail = head;
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this.size = 1;
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}
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/**
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* Adds a data element to the linked list.
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*
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* @param o element to get added
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* @return
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*/
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@Override
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public boolean add(E o)
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{
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this.size++;
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if(this.head == null)
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{
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this.head = new Node<E>(o);
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this.tail = this.head;
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}
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else
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{
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this.tail.setNext(new Node<E>(o));
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this.tail = this.tail.getNext();
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}
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return true;
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}
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/**
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* Checks to see if list contains the element
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*
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* @param o element to see if exists
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* @return
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*/
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@Override
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public boolean contains(E o)
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{
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Node current = this.head;
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while(current != null)
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{
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if(current.getData().equals(o))
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{
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return true;
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}
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current = current.getNext();
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}
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return false;
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}
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/**
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* Returns the size of the linked list
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*
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* @return
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*/
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public int size()
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{
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return this.size;
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}
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/**
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* Removes an element at a specific index in the
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* linked list
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*
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* @param index of element to remove
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* @return element removed, or null if the
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* element is not found
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*/
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public E remove(int index)
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{
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int count = 0;
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Node<E> current = this.head;
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Node<E> previous = null;
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while(current != null)
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{
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if(count == index)
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{
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if(previous == null)
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{
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this.head = current.getNext();
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}
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else
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{
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previous.setNext(current.getNext());
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}
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this.size--;
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return current.getData();
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}
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previous = current;
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current = current.getNext();
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count++;
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}
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return null;
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}
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/**
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* Removes a specific element from the linked list
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*
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* @param o element to remove
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* @return element removed or null if element is not
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* in the list
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*/
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@Override
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public E remove(E o)
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{
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Node<E> current = this.head;
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Node<E> previous = null;
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while(current != null)
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{
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if(current.getData().equals(o))
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{
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if(previous == null)
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{
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this.head = current.getNext();
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}
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else
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{
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previous.setNext(current.getNext());
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}
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this.size--;
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return current.getData();
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}
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previous = current;
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current = current.getNext();
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}
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return null;
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}
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/**
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* Returns the element at a specific index
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* of the linked list.
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*
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* @param index of desired element
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* @return
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*/
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public E get(int index)
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{
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int count = 0;
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Node<E> current = this.head;
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while(current != null)
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{
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if(count == index)
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{
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return current.getData();
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}
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current = current.getNext();
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}
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return null;
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}
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}
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