Created
April 5, 2014 19:14
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Reversing linked list in place
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public class LinkedListReverse { | |
public static void main(String[] args) { | |
Node head = addElement("Monday", null); | |
addElement("Tuesday", head); | |
addElement("Wednesday", head); | |
printList(head); | |
head = reverseList(head); | |
printList(head); | |
} | |
private static Node addElement(Object element, Node head) { | |
Node newElement = new Node(element); | |
if (head == null) { | |
return newElement; | |
} | |
Node current = head; | |
while (current.hasNext()) { | |
current = current.getNext(); | |
} | |
current.setNext(newElement); | |
return head; | |
} | |
private static void printList(Node head) { | |
Node current = head; | |
while (current != null) { | |
System.out.print(current.getElement()); | |
if (current.hasNext()) { | |
System.out.print(", "); | |
} | |
current = current.getNext(); | |
} | |
System.out.println(); | |
} | |
private static Node reverseList(Node head) { | |
Node current = head; | |
Node previous = null; | |
Node next = null; | |
while (current != null) { | |
next = current.getNext(); | |
current.setNext(previous); | |
previous = current; | |
current = next; | |
} | |
return previous; | |
} | |
public static class Node { | |
private final Object element; | |
private Node next; | |
public Node(Object element) { | |
this.element = element; | |
} | |
public Node getNext() { | |
return next; | |
} | |
public void setNext(Node next) { | |
this.next = next; | |
} | |
public boolean hasNext() { | |
return next != null; | |
} | |
public Object getElement() { | |
return element; | |
} | |
} | |
} |
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