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https://github.com/TheAlgorithms/Java.git
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Remove space from Data Structures package name
This commit is contained in:
khalil2535
183
DataStructures/Stacks/NodeStack.java
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183
DataStructures/Stacks/NodeStack.java
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/**
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* Implementation of a stack using nodes.
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* Unlimited size, no arraylist.
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*
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* @author Kyler Smith, 2017
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*/
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public class NodeStack<Item> {
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/**
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* Entry point for the program.
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*/
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public static void main(String[] args) {
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NodeStack<Integer> Stack = new NodeStack<Integer>();
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Stack.push(3);
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Stack.push(4);
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Stack.push(5);
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System.out.println("Testing :");
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Stack.print(); // prints : 5 4 3
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Integer x = Stack.pop(); // x = 5
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Stack.push(1);
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Stack.push(8);
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Integer y = Stack.peek(); // y = 8
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System.out.println("Testing :");
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Stack.print(); // prints : 8 1 4 3
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System.out.println("Testing :");
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System.out.println("x : " + x);
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System.out.println("y : " + y);
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}
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/**
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* Information each node should contain.
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* @value data : information of the value in the node
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* @value head : the head of the stack
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* @value next : the next value from this node
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* @value previous : the last value from this node
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* @value size : size of the stack
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*/
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private Item data;
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private static NodeStack<?> head;
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private NodeStack<?> next;
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private NodeStack<?> previous;
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private static int size = 0;
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/**
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* Constructors for the NodeStack.
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*/
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public NodeStack() {
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}
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private NodeStack(Item item) {
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this.data = item;
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}
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/**
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* Put a value onto the stack.
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*
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* @param item : value to be put on the stack.
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*/
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public void push(Item item) {
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NodeStack<Item> newNs = new NodeStack<Item>(item);
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if(this.isEmpty()) {
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NodeStack.setHead(new NodeStack<>(item));
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newNs.setNext(null);
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newNs.setPrevious(null);
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} else {
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newNs.setPrevious(NodeStack.head);
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NodeStack.head.setNext(newNs);
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NodeStack.head = newNs;
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}
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NodeStack.setSize(NodeStack.getSize() + 1);
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}
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/**
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* Value to be taken off the stack.
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*
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* @return item : value that is returned.
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*/
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public Item pop() {
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Item item = (Item) NodeStack.head.getData();
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NodeStack.head = NodeStack.head.getPrevious();
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NodeStack.head.setNext(null);
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NodeStack.setSize(NodeStack.getSize() - 1);
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return item;
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}
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/**
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* Value that is next to be taken off the stack.
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*
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* @return item : the next value that would be popped off the stack.
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*/
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public Item peek() {
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return (Item) NodeStack.head.getData();
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}
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/**
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* If the stack is empty or there is a value in.
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*
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* @return boolean : whether or not the stack has anything in it.
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*/
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public boolean isEmpty() {
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return NodeStack.getSize() == 0;
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}
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/**
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* Returns the size of the stack.
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*
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* @return int : number of values in the stack.
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*/
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public int size() {
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return NodeStack.getSize();
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}
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/**
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* Print the contents of the stack in the following format.
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*
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* x <- head (next out)
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* y
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* z <- tail (first in)
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* .
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* .
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* .
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*
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*/
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public void print() {
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for(NodeStack<?> n = NodeStack.head; n != null; n = n.previous) {
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System.out.println(n.getData().toString());
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}
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}
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/** Getters and setters (private) */
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private NodeStack<?> getHead() {
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return NodeStack.head;
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}
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private static void setHead(NodeStack<?> ns) {
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NodeStack.head = ns;
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}
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private NodeStack<?> getNext() {
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return next;
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}
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private void setNext(NodeStack<?> next) {
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this.next = next;
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}
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private NodeStack<?> getPrevious() {
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return previous;
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}
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private void setPrevious(NodeStack<?> previous) {
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this.previous = previous;
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}
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private static int getSize() {
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return size;
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}
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private static void setSize(int size) {
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NodeStack.size = size;
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}
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private Item getData() {
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return this.data;
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}
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private void setData(Item item) {
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this.data = item;
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}
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}
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98
DataStructures/Stacks/StackOfLinkedList.java
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98
DataStructures/Stacks/StackOfLinkedList.java
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/**
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*
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* @author Varun Upadhyay (https://github.com/varunu28)
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*
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*/
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// An implementation of a Stack using a Linked List
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class StackOfLinkedList {
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public static void main(String[] args) {
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LinkedListStack stack = new LinkedListStack();
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stack.push(1);
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stack.push(2);
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stack.push(3);
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stack.push(4);
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stack.printStack();
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System.out.println("Size of stack currently is: " + stack.getSize());
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stack.pop();
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stack.pop();
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}
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}
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// A node class
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class Node {
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public int data;
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public Node next;
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public Node(int data) {
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this.data = data;
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this.next = null;
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}
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}
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/**
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* A class which implements a stack using a linked list
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*
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* Contains all the stack methods : push, pop, printStack, isEmpty
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**/
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class LinkedListStack {
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Node head = null;
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int size = 0;
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public void push(int x) {
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Node n = new Node(x);
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if (getSize() == 0) {
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head = n;
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}
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else {
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Node temp = head;
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n.next = temp;
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head = n;
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}
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size++;
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}
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public void pop() {
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if (getSize() == 0) {
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System.out.println("Empty stack. Nothing to pop");
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}
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Node temp = head;
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head = head.next;
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size--;
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System.out.println("Popped element is: " + temp.data);
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}
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public void printStack() {
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Node temp = head;
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System.out.println("Stack is printed as below: ");
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while (temp != null) {
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System.out.print(temp.data + " ");
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temp = temp.next;
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}
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System.out.println();
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}
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public boolean isEmpty() {
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return getSize() == 0;
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}
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public int getSize() {
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return size;
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}
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}
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240
DataStructures/Stacks/Stacks.java
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240
DataStructures/Stacks/Stacks.java
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import java.util.ArrayList;
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/**
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* This class implements a Stack using two different implementations.
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* Stack is used with a regular array and Stack2 uses an ArrayList.
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*
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* A stack is exactly what it sounds like. An element gets added to the top of
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* the stack and only the element on the top may be removed. This is an example
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* of an array implementation of a Stack. So an element can only be added/removed
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* from the end of the array. In theory stack have no fixed size, but with an
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* array implementation it does.
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*
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* @author Unknown
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*
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*/
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class Stack{
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/** The max size of the Stack */
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private int maxSize;
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/** The array representation of the Stack */
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private int[] stackArray;
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/** The top of the stack */
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private int top;
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/**
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* Constructor
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*
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* @param size Size of the Stack
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*/
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public Stack(int size){
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maxSize = size;
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stackArray = new int[maxSize];
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top = -1;
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}
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/**
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* Adds an element to the top of the stack
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*
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* @param value The element added
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*/
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public void push(int value){
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if(!isFull()){ //Checks for a full stack
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top++;
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stackArray[top] = value;
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}else{
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resize(maxSize*2);
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push(value);// don't forget push after resizing
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}
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}
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/**
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* Removes the top element of the stack and returns the value you've removed
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*
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* @return value popped off the Stack
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*/
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public int pop(){
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if(!isEmpty()){ //Checks for an empty stack
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return stackArray[top--];
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}
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if(top < maxSize/4){
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resize(maxSize/2);
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return pop();// don't forget pop after resizing
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}
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else{
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System.out.println("The stack is already empty");
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return -1;
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}
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}
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/**
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* Returns the element at the top of the stack
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*
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* @return element at the top of the stack
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*/
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public int peek(){
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if(!isEmpty()){ //Checks for an empty stack
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return stackArray[top];
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}else{
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System.out.println("The stack is empty, cant peek");
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return -1;
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}
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}
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private void resize(int newSize){
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//private int[] transferArray = new int[newSize]; we can't put modifires here !
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int[] transferArray = new int[newSize];
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//for(int i = 0; i < stackArray.length(); i++){ the length isn't a method .
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for(int i = 0; i < stackArray.length; i++){
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transferArray[i] = stackArray[i];
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stackArray = transferArray;
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}
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maxSize = newSize;
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}
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/**
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* Returns true if the stack is empty
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*
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* @return true if the stack is empty
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*/
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public boolean isEmpty(){
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return(top == -1);
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}
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/**
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* Returns true if the stack is full
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*
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* @return true if the stack is full
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*/
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public boolean isFull(){
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return(top+1 == maxSize);
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}
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/**
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* Deletes everything in the Stack
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*
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* Doesn't delete elements in the array
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* but if you call push method after calling
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* makeEmpty it will overwrite previous
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* values
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*/
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public void makeEmpty(){ //Doesn't delete elements in the array but if you call
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top = -1; //push method after calling makeEmpty it will overwrite previous values
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}
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}
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/**
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* This is an ArrayList Implementation of stack, Where size is not
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* a problem we can extend the stack as much as we want.
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*
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* @author Unknown
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*
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*/
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class Stack2{
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/** ArrayList representation of the stack */
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ArrayList<Integer> stackList;
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/**
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* Constructor
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*/
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Stack2(){
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stackList=new ArrayList<>();
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}
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/**
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* Adds value to the end of list which
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* is the top for stack
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*
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* @param value value to be added
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*/
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void push(int value){
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stackList.add(value);
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}
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/**
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* Pops last element of list which is indeed
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* the top for Stack
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*
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* @return Element popped
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*/
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int pop(){
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if(!isEmpty()){ // checks for an empty Stack
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int popValue=stackList.get(stackList.size()-1);
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stackList.remove(stackList.size()-1); //removes the poped element from the list
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return popValue;
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}
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else{
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System.out.print("The stack is already empty ");
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return -1;
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}
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}
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/**
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* Checks for empty Stack
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*
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* @return true if stack is empty
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*/
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boolean isEmpty(){
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if(stackList.isEmpty())
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return true;
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else return false;
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}
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/**
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* Top element of stack
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*
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* @return top element of stack
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*/
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int peek(){
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return stackList.get(stackList.size()-1);
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}
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}
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/**
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* This class implements the Stack and Stack2 created above
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*
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* @author Unknown
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*
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*/
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public class Stacks{
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/**
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* Main method
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*
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* @param args Command line arguments
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*/
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public static void main(String args[]){
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Stack myStack = new Stack(4); //Declare a stack of maximum size 4
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//Populate the stack
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myStack.push(5);
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myStack.push(8);
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myStack.push(2);
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myStack.push(9);
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System.out.println("*********************Stack Array Implementation*********************");
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System.out.println(myStack.isEmpty()); //will print false
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System.out.println(myStack.isFull()); //will print true
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System.out.println(myStack.peek()); //will print 9
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System.out.println(myStack.pop()); //will print 9
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System.out.println(myStack.peek()); // will print 2
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Stack2 myStack2 = new Stack2(); //Declare a stack of maximum size 4
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//Populate the stack
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myStack2.push(5);
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myStack2.push(8);
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myStack2.push(2);
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myStack2.push(9);
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System.out.println("*********************Stack List Implementation*********************");
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System.out.println(myStack2.isEmpty()); //will print false
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System.out.println(myStack2.peek()); //will print 9
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System.out.println(myStack2.pop()); //will print 9
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System.out.println(myStack2.peek()); // will print 2
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System.out.println(myStack2.pop()); //will print 2
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}
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}
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