Understanding how link list works - java

I was given this code to write multiple classes with, but i am having a hard time understand this LinkList. When calling my clear() and my count(E o) method(which are two that is required to write) I am not sure how to run the loop. I am not sure what is referenced has my .length of the array I would call in my class, and keep getting nullpointers. Is size the right variable or should it be something else? Also a bit confused on who to call count(E o) in the main method.
public class GenericLinkedList<E> implements List<E> {
private class Node<E>{
private E data;
private Node<E> next;
}
private E data;
private Node<E> head = null;
private int size = 0;
private Node<E> nodeAt(int index){
Node<E> curNode = head;
int curIndex = 0;
while(curIndex < index){
curNode = curNode.next;
curIndex++;
}
return curNode;
}
#Override
public E get(int index) {
return nodeAt(index).data;
}
#Override
public void add(E value) {
Node<E> node = new Node<E>();
node.data = value;
if(size == 0){
head = node;
}else{
Node<E> curNode = nodeAt(size - 1);
curNode.next = node;
}
size++;
}
public void add(int index, E value){
Node<E> node = new Node<E>();
node.data = value;
if(size == 0){
head = node;
}else if(index == 0){
node.next = head;
head = node;
}else{
Node<E> curNode = nodeAt(index - 1);
node.next = curNode.next;
curNode.next = node;
}
size++;
}
#Override
public void remove(int index) {
if(index == 0){
head = head.next;
}else{
Node<E> curNode = nodeAt(index - 1);
curNode.next = curNode.next.next;
}
}
#Override
public void set(int index, E value) {
nodeAt(index).data = value;
}
public String toString(){
String s = "";
Node<E> curNode = head;
s += curNode.data +" -> ";
while(curNode.next != null){
curNode = curNode.next;
s += curNode.data +" -> ";
}
s += "null";
return s;
}
#Override
public void clear()//Clears out the array object by setting everything to null
{
for(int i = 0; i < data.size; i++)
{
remove(0);
}
}
#Override
public int count()
{
int count = 0;
E temp;
for(int i = 0;i<size-1;i++)
{
if(get(i)!=null)
{
count++;
}
else
{
}
}
return count;
}

Related

Interval search in Binary Tree

Can someone help me with the interval search in binary tree.
I understand how to check left side of the tree,but I have troubles with chicking right side of it.
This is my code by now.
private boolean search(BSTNode r, int from,int till){
boolean found = false;
int arr[];
arr=new int[10];
int i=0;
while (r != null)
{
int rval = r.getData();
if (from < rval && till >rval) {
r = r.getLeft();
arr[i]=rval;
i++;
}else
r=r.getRight();
}
return found;
}
This is full class of BSTNode.
From and till it is range of interval(from
class BSTNode
{
BSTNode left, right;
int data;
/* Constructor */
public BSTNode()
{
left = null;
right = null;
data = 0;
}
/* Constructor */
public BSTNode(int n)
{
left = null;
right = null;
data = n;
}
/* Function to set left node */
public void setLeft(BSTNode n)
{
left = n;
}
/* Function to set right node */
public void setRight(BSTNode n)
{
right = n;
}
/* Function to get left node */
public BSTNode getLeft()
{
return left;
}
/* Function to get right node */
public BSTNode getRight()
{
return right;
}
You can search by using queue like this:
public boolean search(Integer from, Integer till) {
return search(root, from, till);
}
private boolean search(BSTNode root, Integer from, Integer till) {
boolean found = false;
Queue<BSTNode> queue = new ArrayDeque<>();
queue.add(root);
List<Integer> list = new ArrayList<>();
while (!queue.isEmpty()) {
BSTNode node = queue.poll();
int data = node.getData();
if (from < data && till > data) {
found = true;
list.add(data);
}
if (node.getLeft() != null)
queue.add(node.getLeft());
if (node.getRight() != null)
queue.add(node.getRight());
}
System.out.println(list);
return found;
}
, full code
public static void main(String[] args) {
BinarySearchTree tree = new BinarySearchTree();
// Tree building...
tree.insert(50);
tree.insert(40);
tree.insert(20);
tree.insert(10);
tree.insert(50);
System.out.println(tree.search(10, 30));
}
static class BinarySearchTree {
private BSTNode root;
public void insert(Integer item) {
root = insert(root, item);
}
private BSTNode insert(BSTNode node, Integer item) {
if (node == null) {
return new BSTNode(item);
} else if (item.compareTo(node.data) == 0) {
return node;
} else if (item.compareTo(node.data) < 0) {
node.setRight(insert(node.r, item));
return node;
} else {
node.setLeft(insert(node.l, item));
return node;
}
}
public Integer find(Integer target) {
return find(root, target);
}
private Integer find(BSTNode node, Integer target) {
if (node == null) {
return null;
}
Integer cmd = target.compareTo(node.data);
if (cmd == 0) {
return node.data;
} else if (cmd < 0) {
return find(node.getRight(), target);
} else {
return find(node.getLeft(), target);
}
}
public boolean search(Integer from, Integer till) {
return search(root, from, till);
}
private boolean search(BSTNode root, Integer from, Integer till) {
boolean found = false;
Queue<BSTNode> queue = new ArrayDeque<>();
queue.add(root);
List<Integer> list = new ArrayList<>();
while (!queue.isEmpty()) {
BSTNode node = queue.poll();
int data = node.getData();
if (from < data && till > data) {
found = true;
list.add(data);
}
if (node.getLeft() != null)
queue.add(node.getLeft());
if (node.getRight() != null)
queue.add(node.getRight());
}
System.out.println(list);
return found;
}
}
static class BSTNode {
Integer data;
BSTNode l = null;
BSTNode r = null;
public BSTNode(Integer data) {
super();
this.data = data;
}
public Integer getData() {
return data;
}
public void setData(int data) {
this.data = data;
}
public BSTNode getLeft() {
return l;
}
public void setLeft(BSTNode l) {
this.l = l;
}
public BSTNode getRight() {
return r;
}
public void setRight(BSTNode r) {
this.r = r;
}
#Override
public String toString() {
return "BSTNode [data=" + data + ", l=" + l + ", r=" + r + "]";
}
}
, the output
[20]
true

Queue reverse implementation - code not working

I'm new to programming and trying to implement an algorithm which reverse K elements in a queue using linkedlist and stack but for some reason, I'm not able to execute the algorithm, any help is greatly appreciated.
I found queue is coming as empty eventhough I add values to it & I see added values in console but when I checked queue.isEmpty() is coming as true.
Here is my code
public class QueueReverseK {
public void reverse(QueueADT queue, int k) {
if (queue.isEmpty()) {
System.out.println("in if empty");
return;
}
if (k > queue.size()) {
k = queue.size;
} else if (k < 0) {
k = 0;
}
StackADT tempStack = new StackADT(k);
QueueADT newQueue = new QueueADT();
for (int i = 0; i < k; i++) {
tempStack.push(queue.deQueue().getData());
}
while (!tempStack.isEmpty()) {
newQueue.enQueue(tempStack.pop());
}
while (!queue.isEmpty()) {
newQueue.enQueue(queue.deQueue().getData());
}
queue = newQueue;
}
Queue class
public class Queue {
LinkedList items;
int size;
Node head;
Node tail;
LinkedListADT list = new LinkedListADT();
public Queue() {
items = new LinkedList();
size = 0;
head = null;
tail = null;
}
public int size() {
return size;
}
public boolean isEmpty() {
if (head == null) return true;
else return false;
}
public void enQueue(int i) {
items.addHead(i);
}
public Node deQueue() {
return items.deleteHead();
}
public void printQueue() {
items.printList();
}
}
LinkedList Class
public class LinkedList {
Node head;
Node tail;
LinkedList() {
head = null;
tail = null;
}
public void addHead(int val) {
Node n = new Node(val);
if (head == null) {
head = n;
tail = n;
} else {
Node tempNode = head;
while (tempNode.next != null) {
tempNode = tempNode.next;
}
tempNode.next = n;
}
}
public void addTail(int val) {
Node n = new Node(val);
if (head == null) {
head = n;
tail = n;
} else {
tail.next = n;
tail = n;
}
}
public int deleteTail() {
Node n = tail;
if (head == null) {
return -1;
} else if (head == tail) {
head = null;
tail = null;
} else {
Node cur = head;
while (cur.getNext() != tail)
cur = cur.next;
tail = cur;
tail.next = null;
}
return n.getData();
}
public Node deleteHead() {
Node n = head;
head = head.next;
return n;
}
public int count() {
int size = 0;
Node n = head;
while (n != null) {
n = n.getNext();
size++;
}
return size;
}
public Node getHead() {
return head;
}
public void setHead(Node head) {
this.head = head;
}
public Node getTail() {
return tail;
}
public void setTail(Node tail) {
this.tail = tail;
}
public void printList() {
if (this.head == null) {
return;
}
// print all nodes
Node tempNode = this.head;
while (tempNode != null) {
System.out.print(tempNode.data + "->");
tempNode = tempNode.next;
}
}
void printMiddle(int n) {
Node slow_ptr = head;
Node fast_ptr = head;
if (head != null) {
while (fast_ptr != null && fast_ptr.next != null) {
fast_ptr = fast_ptr.next.next;
slow_ptr = slow_ptr.next;
}
System.out.print(slow_ptr.data + " ");
for (int i = 1; i <= n && slow_ptr != null; i++) {
slow_ptr = slow_ptr.next;
System.out.print(slow_ptr.data + " ");
}
}
}
}
Main Class
public static void main(String[] args) {
Queue Q = new Queue();
Q.enQueue(1);
Q.enQueue(2);
Q.enQueue(3);
Q.enQueue(4);
QueueReverseK k = new QueueReverseK();
k.reverse(Q, 2)
Q.printQueue();
}
Stack Class
public class Stack {
private int top;
private int items[];
private int max;
public StackADT(int n) {
this.max = n;
top = 0;
items = new int[n];
}
public boolean isEmpty() {
return top == 0;
}
public boolean isFull() {
return top == max;
}
public void push(int item) {
if (isFull()) throw new IllegalArgumentException();
else items[top++] = item;
}
public int pop() {
if (isEmpty()) throw new IllegalArgumentException();
else return items[--top];
}
public int size() {
return top;
}
}
}
Example
input Queue: 12 34 65 76 23 12 36 90
output Queue : 12 34 65 76 90 36 12 23
I'm not entirely positive, but it looks like your queue is acting like a stack. You're enQueue is pushing to the head, not the tail of the queue.

AVL Tree gives me O(c^n) instead of O(log n)

I've created an AVLTree in java and the add method should be of O(log n)... However my add method seems to give me a graph of O(c^n) or an exponential graph instead of a logarithmic graph. Here is the graph of running time vs input size:
Can anyone help figure out as to why this happens?
Here is the code for my AVLTree:
import java.util.ArrayList;
import java.util.Comparator;
import java.util.Iterator;
import cw1.rs10.lib.IAVLTree;
public class AVLTree<K, V> implements IAVLTree<K, V>
{
public class Node {
private K key;
private ArrayList<V> values;
private Node left, right;
private int height;
public Node(K key, V value) {
this.key = key;
this.values = new ArrayList<V>();
this.left = null;
this.right = null;
this.height = 0;
values.add(value);
}
public K getKey() {
return key;
}
public void setKey(K key) {
this.key = key;
}
public ArrayList<V> getValues() {
return values;
}
public void addValue(V value) {
values.add(value);
}
public Node getLeft() {
return left;
}
public Node getRight() {
return right;
}
public void setLeft(Node left) {
this.left = left;
}
public void setRight(Node right) {
this.right = right;
}
public int getHeight() {
return height;
}
public void setHeight(int height) {
this.height = height;
}
}
private Node rootNode;
private Comparator<K> comparator;
//Unused
public AVLTree() {
}
public AVLTree(Comparator<K> comparator) {
this.rootNode = null;
this.comparator = comparator;
}
#Override
public V add(K k, V v) {
Node n = rootNode = add(k, v, rootNode);
if(n != null)
return v;
else
return null;
}
private Node add(K key, V value, Node node) {
if(node == null)
return new Node(key, value);
if(comparator.compare(key, node.getKey()) < 0) {
node.setLeft(add(key, value, node.getLeft()));
if(height(node.getLeft()) - height(node.getRight()) == 2) {
if(comparator.compare(key, node.getLeft().getKey()) < 0)
node = rotateLeft(node);
else
node = doubleRotateLeft(node);
}
} else if(comparator.compare(key, node.getKey()) > 0) {
node.setRight(add(key, value, node.getRight()));
if(height(node.getRight()) - height(node.getLeft()) == 2) {
if(comparator.compare(key, node.getRight().getKey()) > 0)
node = rotateRight(node);
else
node = doubleRotateRight(node);
}
} else {
//Handle duplicate
node.getValues().add(value);
}
node.setHeight( Math.max(height(node.getLeft()), height(node.getRight())) + 1 );
return node;
}
#Override
public V remove(K key, V value) throws Exception {
Node node = rootNode = remove(key, value, rootNode);
if(node != null)
return value;
else
return null;
}
private Node remove(K key, V value, Node node) {
//If node with key contains one or less values, remove the whole key
//Else remove value from node with key
if(node == null) return null;
else if(comparator.compare(key, node.getKey()) < 0) {
node.setLeft(remove(key, value, node.getLeft()));
if(height(node.getLeft()) - height(node.getRight()) == 2) {
if(comparator.compare(key, node.getLeft().key) < 0)
node = rotateLeft(node);
else
node = doubleRotateLeft(node);
}
} else if(comparator.compare(key, node.getKey()) > 0) {
node.setRight(remove(key, value, node.getRight()));
if(height(node.getRight()) - height(node.getLeft()) == 2) {
if(comparator.compare(key, node.getRight().key) < 0)
node = rotateRight(node);
else
node = doubleRotateRight(node);
}
} else {
if(node.getValues().size() > 1) {
node.getValues().remove(value);
return node;
} else {
if(node.getLeft() == null && node.getRight() == null)
return null;
if(node.getLeft() == null) return node.getRight();
if(node.getRight() == null) return node.getLeft();
Node smallestNode = smallestNode(node.getRight());
node = smallestNode;
node.setRight(remove(key, value, node.getRight()));
return node;
}
}
return node;
}
#Override
public Iterator<V> find(K key) {
Node n = search(key, rootNode);
if(n != null) {
ArrayList<V> values = n.getValues();
return values.iterator();
} else {
return new ArrayList<V>().iterator();
}
}
private Node search(K key, Node node) {
while(node != null) {
if(comparator.compare(key, node.getKey()) < 0)
node = node.getLeft();
else if(comparator.compare(key, node.getKey()) > 0)
node = node.getRight();
else
return node;
}
return null;
}
#Override
public Iterator<V> removeAll(K key) {
Node n = search(key, rootNode);
ArrayList<V> values = n.getValues();
try {
remove(n.getKey(), null);
} catch (Exception e) {
e.printStackTrace();
}
return values.iterator();
}
#Override
public Iterator<V> listAll() {
ArrayList<V> entries = new ArrayList<V>();
listAll(rootNode, entries);
return entries.iterator();
}
private void listAll(Node n, ArrayList<V> entries) {
if(n != null) {
listAll(n.getLeft(), entries);
entries.addAll(n.getValues());
listAll(n.getRight(), entries);
}
}
#Override
public int height() {
return height(rootNode);
}
//Custom Methods
/**
* A method to test if the tree is logically empty
*
* #return true if empty, false if not
*/
public boolean isEmpty() {
return rootNode == null;
}
/**
* Logically empties the tree by setting the rootNode to null
*/
public void empty() {
rootNode = null;
}
public void inOrderTraversal(Node node) {
if(node != null) {
inOrderTraversal(node.getLeft());
System.out.print(node.getKey() + ", ");
inOrderTraversal(node.getRight());
}
}
public int height(Node node) {
if(node == null) return -1;
else return node.height;
}
public Node getRootNode() {
return rootNode;
}
public Node smallestNode(Node node) {
if(node.getLeft() == null)
return node;
return smallestNode(node.getLeft());
}
private Node rotateLeft(Node node2) {
Node node1 = node2.getLeft();
node2.setLeft(node1.getRight());
node1.setRight(node2);
node2.setHeight(Math.max(height(node2.getLeft()), height(node2.getRight())) + 1);
node1.setHeight(Math.max(height(node1.getLeft()), node2.getHeight()) + 1);
return node1;
}
private Node rotateRight(Node node1) {
Node node2 = node1.getRight();
node1.setRight(node2.getLeft());
node2.setLeft(node1);
node1.setHeight(Math.max(height(node1.getLeft()), height(node1.getRight())) + 1);
node2.setHeight(Math.max(height(node2.getRight()), node1.getHeight()) + 1);
return node2;
}
private Node doubleRotateLeft(Node node3) {
node3.setLeft(rotateRight(node3.getLeft()));
return rotateLeft(node3);
}
private Node doubleRotateRight(Node node1) {
node1.setRight(rotateLeft(node1.getRight()));
return rotateRight(node1);
}
}
The interface for my AVLTree:
import java.util.Iterator;
public interface IAVLTree<K,V>
{
public V add(K k, V v);
public V remove(K k, V v);
public Iterator<V> removeAll(K k);
public Iterator<V> find(K k);
public Iterator<V> listAll();
public int height();
}
And finally, my testing code:
public class AVLTest
{
private static long startTime, endTime;
private static int amountOfCommands = 10000;
public static void main(String[] args) {
AVLTree<String, Integer> tree = new AVLTree<String, Integer>(String.CASE_INSENSITIVE_ORDER);
try {
startTime = System.currentTimeMillis();
for (int i = 1; i <= amountOfCommands; i++) {
String key = "K" + i;
tree.add(key, i);
}
endTime = System.currentTimeMillis();
} catch(Exception e) {
e.printStackTrace();
}
long runningTime = endTime - startTime;
System.out.println("Running Time: " + runningTime + "ms\nNo. of Commands: " + amountOfCommands);
}
}
You are measuring it wrong. Your test code measures the time to add all of the elements in the tree, instead of just one.
startTime = System.currentTimeMillis();
for (int i = 1; i <= amountOfCommands; i++) {
String key = "K" + i;
tree.add(key, i);
}
endTime = System.currentTimeMillis();
What you want to measure is the time it takes to add one node to the tree as a function of the number of nodes already in the tree.
for (int i = 1; i < amountOfCommands; i++) { // note the < instead of <=
String key = "K" + i;
tree.add(key, i);
}
String key = "K" + amountOfCommands;
startTime = System.currentTimeMillis();
tree.add(key, amountOfCommands);
endTime = System.currentTimeMillis();
Of course you can run your test more efficiently if you reuse the same tree for all measurements. I'll leave it to you.

QuickSort with Double Linked List

I am having trouble with my swap method in the Quick Sort program. I'm implementing it from a QuickSort method that sorts arrays. Here I take in a file with an integer on each line, it puts the number in a doubly linked list and then sorts the list and outputs to a new file. I need help with the swap method and what else I need to add or do to make it work properly. Any advise would help and examples are best. Thank you
//swap A[pos1] and A[pos2]
public static void swap(DList A, int pos1, int pos2){
int temp = A.get(pos1);
A[pos1] = A[pos2];
A[pos2] = temp;
}
My entire program for quicksort looks like this:
import java.util.*;
import java.io.*;
public class Test_QuickSort{
private static Scanner input = new Scanner(System.in);
private static DList list = new DList();
public static void main(String[] args) throws FileNotFoundException
{
input = new Scanner(new File("data.txt"));
while (input.hasNext())
{
String s = input.nextLine();
DNode g = new DNode(Integer.parseInt(s));
list.addLast(g);
}
//int[] A = {1,4,6,2};
QuickSort(list, 0, list.size()-1);
//for(int i = 0; i < A.length; i++)
// System.out.print(A[i] + " ");
}
public static void QuickSort(DList A, int left, int right){
if(left >= right)
return;
int pivot_index = partition(A, left, right);
QuickSort(A, left, pivot_index - 1);
QuickSort(A, pivot_index + 1, right);
}
public static int partition(DList A, int left, int right){
int pivot = A.get(right);
int index = left;
for(int i = left; i < right; i++){
if(A.get(i) <= pivot){
swap(A, index, i);
index ++;
}
}
swap(A, index, right);
return index;
}
//swap A[pos1] and A[pos2]
public static void swap(DList A, int pos1, int pos2){
int temp = A.get(pos1);
A[pos1] = A[pos2];
A[pos2] = temp;
}
}
My DList Method looks like this:
class DNode {
protected int element; // String element stored by a node
protected DNode next, prev; // Pointers to next and previous nodes
public DNode(int e)
{
element = e;
prev = null;
next = null;
}
public DNode()
{
element = 0;
next = null;
prev = null;
}
public DNode(int e, DNode p, DNode n) {
element = e;
prev = p;
next = n;
}
public int getElement() {
return element; }
public DNode getPrev() {
return prev; }
public DNode getNext() {
return next; }
public void setElement(int newElem) { element = newElem; }
public void setPrev(DNode newPrev) { prev = newPrev; }
public void setNext(DNode newNext) { next = newNext; }
}
public class DList {
protected int size;
protected DNode header, trailer;
public DList() {
size = 0;
header = new DNode(0, null, null);
trailer = new DNode(0, header, null);
header.setNext(trailer);
}
public int size() {
return size; }
public boolean isEmpty() {
return (size == 0); }
public DNode getFirst() throws IllegalStateException {
if (isEmpty()) throw new IllegalStateException("List is empty");
return header.getNext();
}
public DNode getLast() throws IllegalStateException {
if (isEmpty()) throw new IllegalStateException("List is empty");
return trailer.getPrev();
}
public DNode getPrev(DNode v) throws IllegalArgumentException {
if (v == header) throw new IllegalArgumentException
("Cannot move back past the header of the list");
return v.getPrev();
}
public int get(int pos)
{
DNode current = new DNode();
for(int i = 0; i <= pos && current != null; i++)
{
if(pos == 0){
current = header;
}
else{
current = current.next;
break;
}
}
return current.element;
}
public DNode getNext(DNode v) throws IllegalArgumentException {
if (v == trailer) throw new IllegalArgumentException
("Cannot move forward past the trailer of the list");
return v.getNext();
}
public void addBefore(DNode v, DNode z) throws IllegalArgumentException {
DNode u = getPrev(v); // may throw an IllegalArgumentException
z.setPrev(u);
z.setNext(v);
v.setPrev(z);
u.setNext(z);
size++;
}
public void addAfter(DNode v, DNode z) {
DNode w = getNext(v); // may throw an IllegalArgumentException
z.setPrev(v);
z.setNext(w);
w.setPrev(z);
v.setNext(z);
size++;
}
public void addFirst(DNode v) {
addAfter(header, v);
}
public void addLast(DNode v) {
addBefore(trailer, v);
}
public boolean hasPrev(DNode v) {
return v != header; }
public boolean hasNext(DNode v) {
return v != trailer; }
public String toString() {
String s = "[";
DNode v = header.getNext();
while (v != trailer) {
s += v.getElement();
v = v.getNext();
if (v != trailer)
s += ",";
}
s += "]";
return s;
}
}
The reason you are always retrieving the same element in DList.get is that you stop looping after the first iteration. Simply remove the break-statement, and the loop should work as intended.
public int get(int pos)
{
DNode current = new DNode();
for(int i = 0; i <= pos && current != null; i++)
{
if(pos == 0){
current = header;
}
else{
current = current.next;
// break; <-- remove this
}
}
return current.element;
}
Side note: You could get rid of the if-statement, if you would initialize current to header:
public int get(int pos)
{
DNode current = header;
for(int i = 1; i <= pos && current != null; i++)
{
current = current.next;
}
return current.element;
}
Now regarding your swap-method: As already stated, you try to treat the instance of DList as an array by trying to dereference an element using square-brackets. Instead, you should implement a method in DList that allows setting an element at a certain position. For example:
public void setAt(int pos, int value){
DNode current = header;
for(int i = 1; i <= pos && current != null; i++){
current = current.next;
}
if(current != null)
current.setElement(value);
else
throw new IndexOutOfBoundsException();
}
Now you can change your swap-method to:
public static void swap(DList a, int pos1, int pos2){
int temp = a.get(pos1);
a.setAt(pos1, a.get(pos2));
a.setAt(pos2, temp);
}

Iterating through the Circular linked list

I am dealing with the following problem.
I have created a circular list, and i am also able to create x number of nodes for the number of people required in the circle. I am however stuck as i do not know how exactly i will iterate through the list for every nth person(node). I think i will need to create my own iterator but not sure how to go about it. I know it might be possible to import one from library but i don't want to do that as that will kill the learning process for me.
Here is the code for my Node Class
public class Node {
public int iData;
public Node next;
public Node(int x) {
iData = x;
}
public void displayNode() {
System.out.print(iData + " ");
}
}
Here is the code for Circular Linked List
public class CircularList {
private Node first;
private Node last;
private Node current;
private int count; // total items in the list
public CircularList getCurrent;
public CircularList() {
first = null;
last = null;
current = null;
count = 0;
}
public boolean isEmpty() {
return first == null;
}
public void step() {
current = current.next;
}
public Node getCurrent() {
return current;
}
public void insert(int x) {
Node newNode = new Node(x);
if (isEmpty()) {
first = newNode;
current = first;
} else {
current.next = newNode;
}
newNode.next = first;
last = newNode;
step();
count++;
}
public boolean search(int x) {
Node search = first;
int y = 0;
while (search.iData != x && y < count) {
search = search.next;
y++;
}
if (search.iData == x) {
System.out.println("Found the value: " + search.iData);
return true;
} else {
System.out.println("Value not found in list");
return false;
}
}
public void delete(int x) {
Node prev = first;
Node curr = first.next;
int y = 0;
while (y < count && curr.iData != x) {
prev = curr;
curr = curr.next;
}
if (count == 1) {
first = null;
count--;
} else {
prev.next = curr.next;
count--;
}
}
public void displayList() {
int x = 0;
Node printer = first;
while (x < count) {
printer.displayNode();
printer = printer.next;
x++;
}
}
}
Here is the code for my Josephus Class
public class Josephus {
private int numOfPeople; // number of people in a circle
private int countNum; // number used for counting off
CircularList circle;
public Josephus() {
circle = new CircularList();
numOfPeople = 0;
countNum = 0;
}
public void setNumOfPeople(int x) {
numOfPeople = x;
}
public int getNumOfPeople() {
return numOfPeople;
}
public void setCountNum(int x) {
countNum = x;
}
public int getcountNum() {
return countNum;
}
public void addPeople(int x) {
for (int i = 1; i < x; i++) {
circle.insert(i);
}
}
public void display() {
circle.displayList();
}
}
I need guidance in the right direction as to what i should do now. I do not ask for code or the answer. i want someone to push me towards the solutions. I can't go to sleep unless i solve this tonight.

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