/**
* Adds a node to the beginning of the list.
*
* @param node the node to add to the beginning of the list.
*/
public LinkedListNode addFirst(LinkedListNode node) {
node.next = head.next;
node.previous = head;
node.previous.next = node;
node.next.previous = node;
return node;
}
// return the head of the new linked list
public static LinkedListNode partitionAround(LinkedListNode ll, int x) {
// start from a list with only one node
// we are actually creating a new linked list
LinkedListNode head = ll;
LinkedListNode tail = ll;
while (ll != null) {
// because the current node ll will be moved, we have to
// save the next node for the loop to continue
LinkedListNode next = ll.next;
if (ll.data < x) {
// prepend the node
ll.next = head;
// update the head
head = ll;
} else {
// append the node
tail.next = ll;
// update the tail
tail = ll;
}
ll = next;
}
tail.next = null;
return head;
}
public static void main(String[] args) {
LinkedListNode node1 = new LinkedListNode(10);
LinkedListNode node2 = new LinkedListNode(15);
LinkedListNode node3 = new LinkedListNode(12);
node1.next = node2;
node2.next = node3;
System.out.println(getNthFromLast(1, node1));
}
public static LinkedListNode buildList(int[] A) {
LinkedListNode head = new LinkedListNode(A[0]);
for (i = 1; i < A.length; i++) {
head.next = new LinkedListNode(A[i]);
head = head.next;
}
return head;
}
public static boolean deleteNode(LinkedListNode n) {
if (n == null || n.next == null) return false;
n.data = n.next.data;
n.next = n.next.next;
return true;
}
private LinkedListNode getLastNode(LinkedListNode node) {
while (node.getNext() != null) {
node = node.getNext();
}
return node;
}
public int hashCode() {
final int PRIME = 31;
int result = 1;
for (LinkedListNode node = this.firstNode; node != null; node = node.getNext()) {
result = PRIME * result + node.hashCode();
}
return result;
}
/**
* Returns a String representation of the linked list with a comma delimited list of all the
* elements in the list.
*
* @return a String representation of the LinkedList.
*/
public String toString() {
LinkedListNode node = head.next;
StringBuilder buf = new StringBuilder();
while (node != head) {
buf.append(node.toString()).append(", ");
node = node.next;
}
return buf.toString();
}
Boolean deleteMiddleGivenNode(LinkedListNode n) {
if (n == null || n.next == null) {
return false;
}
LinkedListNode nextNode = n.next;
n.data = nextNode.data;
n.next = nextNode.next;
return true;
}
/** Remove tail node */
public void deleteLast() {
// set a LinkedListNode to get the current Node
LinkedListNode<T> currentNode = head;
// when the next to next node is null
while (currentNode.getNext().getNext() != null) {
currentNode = currentNode.getNext();
}
// set the current node to be null
currentNode.setNext(null);
}
/** Insert a new node with data after currentNode */
public void insertAfter(LinkedListNode<T> currentNode, T data) {
// create a new linkedListNode
LinkedListNode<T> newNode = new LinkedListNode<T>();
// assign that node some data
newNode.setData(data);
// point new node where current pointer is
newNode.setNext(currentNode.getNext());
// set head pointer to this new node
currentNode.setNext(newNode);
}
static void deleteFastNode(LinkedListNode node) {
if (node == null) return;
LinkedListNode node1 = node.next;
if (node1 != null) {
node.next = node1.next;
node.value = node1.value;
} else {
node = null;
}
}
public static void main(String[] args) {
LinkedListNode node1 = new LinkedListNode(10);
LinkedListNode node2 = new LinkedListNode(15);
LinkedListNode node3 = new LinkedListNode(12);
node1.next = node2;
node2.next = node3;
printList(node1);
deleteFastNode(node1);
printList(node1);
}
public static void traverse(LinkedListNode head) {
if (head == null) return;
StringBuffer buffer = new StringBuffer();
while (head != null) {
buffer.append(head.getData() + "->");
// remember to move
head = head.getNext();
}
buffer.append("null");
System.out.println(buffer.toString());
}
/** Erases all elements in the list and re-initializes it. */
public void clear() {
// Remove all references in the list.
LinkedListNode node = getLast();
while (node != null) {
node.remove();
node = getLast();
}
// Re-initialize.
head.next = head.previous = head;
}
// Floyd's algorithm
public boolean isCyclic(LinkedList list) {
LinkedListNode slowPtr = list.getHead(), fastPtr = list.getHead();
while (fastPtr != null && slowPtr != null) {
fastPtr = fastPtr.getNext();
if (fastPtr == slowPtr) return true;
if (fastPtr == null) return false;
fastPtr = fastPtr.getNext();
if (fastPtr == slowPtr) return true;
slowPtr = slowPtr.getNext();
}
return false;
}
/** Return the number of nodes in this list. */
public int size() {
// set a LinkedListNode to get the current Node
LinkedListNode<T> currentNode = head;
int listSize = 0;
// As long as there is a node with data after the current Node
while (currentNode != null) {
listSize = listSize + 1;
// shift to set the next node as the current Node
currentNode = currentNode.getNext();
}
return listSize;
}
/** Get the tail node of the list. */
public LinkedListNode<T> getLastNode() {
// set a LinkedListNode to get the current Node
LinkedListNode<T> currentNode = head;
// As long as there is a node with data after the current Node
while (currentNode.getNext() != null) {
// shift to set the next node as the current Node
currentNode = currentNode.getNext();
}
// When there is no node after the current Node return the data in the
// current Node
return currentNode;
}
public void removeDuplicatesUsingMaps(LinkedListNode n) {
HashSet<Integer> set = new HashSet<Integer>();
LinkedListNode previous = null;
while (n.next != null) {
if (set.contains(n.data)) {
previous.next = n.next;
} else {
set.add(n.data);
previous = n;
}
n = n.next;
}
}
/* Insert key and value into hash table. */
public void put(K key, V value) {
LinkedListNode<K, V> node = getNodeForKey(key);
if (node != null) {
node.value = value; // just update the value.
return;
}
node = new LinkedListNode<K, V>(key, value);
int index = getIndexForKey(key);
if (arr.get(index) != null) {
node.next = arr.get(index);
node.next.prev = node;
}
arr.set(index, node);
}
public void removeDuplicatesUsingTwoPointers(LinkedListNode n) {
LinkedListNode p1 = n;
while (p1.next != null) {
LinkedListNode p2 = p1;
while (p2.next != null) {
if (p2.next.data == p1.data) {
p2.next = p2.next.next;
} else {
p2 = p2.next;
}
}
p1 = p1.next;
}
}
/**
* Remove the last node from the list. The previous node then becomes the last node. If this is
* the last node then both first and last node references are set to null.
*
* @return The first <code>LinkedListNode</code>.
*/
public LinkedListNode removeLast() {
if (this.lastNode == null) {
return null;
}
final LinkedListNode node = this.lastNode;
this.lastNode = node.getPrevious();
node.setPrevious(null);
if (this.lastNode != null) {
this.lastNode.setNext(null);
} else {
this.firstNode = this.lastNode;
}
this.size--;
return node;
}
public void insert(int[] array, int startIndex) {
for (int i = startIndex; i < array.length; i++) {
LinkedListNode node = new LinkedListNode(array[i]);
tail.next = node;
tail = node;
}
}
/** Return a String representation of the list. */
public String toString() {
// set a LinkedListNode to get the current Node
LinkedListNode<T> currentNode = head;
String s = "{";
// As long as there is a node with data after the current Node
while (currentNode != null) {
s = s + " " + currentNode.getData();
// shift to set the next node as the current Node
currentNode = currentNode.getNext();
}
// When there is no node after the current Node return the data in the
// current Node
s = s + "}";
System.out.println("The list is " + s);
return s;
}
public static void main(String[] args) {
LinkedListNode node = method.randomLinkedList(10, 0, 10);
System.out.println(node.printForward());
int nth = 2;
LinkedListNode n = nthNode(node, nth);
try {
FileWriter write = new FileWriter("findn.txt");
PrintWriter out = new PrintWriter(write);
if (n != null) out.println(nth + "th to last node is " + n.data);
else out.println("null");
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}
public void Search(String s) // Returns nothing if its empty, else goes to LLN to search.
{
if (head != null) head.Search(s);
if (head == null)
System.out.println(s + " wasn't found but would be at the beginning of the list.");
System.out.println();
}
public String printForward() {
String data = "(" + key + "," + value + ")";
if (next != null) {
return data + "->" + next.printForward();
} else {
return data;
}
}
@Override
public String toString() {
LinkedListNode node = head;
String res = new String("[");
while (node != null) {
res = res + node.value();
if (node.next() != null) {
res = res + ", ";
}
node = node.next();
}
res = res + "]";
return res;
}
// finds the starting node of the cycle
public LinkedListNode findLoopStart(LinkedList list) {
LinkedListNode slowPtr = list.getHead(), fastPtr = list.getHead();
boolean cyclic = false;
while (slowPtr != null && fastPtr != null) {
fastPtr = fastPtr.getNext();
if (fastPtr == slowPtr) {
cyclic = true;
break;
}
if (fastPtr == null) {
cyclic = false;
break;
}
fastPtr = fastPtr.getNext();
if (fastPtr == slowPtr) {
cyclic = true;
break;
}
slowPtr = slowPtr.getNext();
}
// if cycle exists
if (cyclic) {
slowPtr = list.getHead();
while (slowPtr != fastPtr) {
slowPtr = slowPtr.getNext();
fastPtr = fastPtr.getNext();
}
return slowPtr;
}
return null;
}
public void insert(LinkedListNode node) {
if (head == null) {
head = node;
tail = node;
} else {
tail.next = node;
tail = node;
}
}
