113 lines
2.3 KiB
Java
113 lines
2.3 KiB
Java
package DataStructures.Stacks;
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/**
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* @author Varun Upadhyay (https://github.com/varunu28)
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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.push(5);
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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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System.out.println("Top element of stack currently is: " + stack.peek());
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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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* <p>
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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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public void push(int x) {
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Node n = new Node(x);
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if (head == null) {
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head = n;
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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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}
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public void pop() {
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if (head == null) {
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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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System.out.println("Popped element is: " + temp.data);
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}
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public int peek() {
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if (head == null) {
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return -1;
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}
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return head.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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if (temp.next == null) {
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System.out.print(temp.data);
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} else {
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System.out.print(temp.data + " -> ");
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}
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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 head == null;
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}
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public int getSize() {
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if (head == null)
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return 0;
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else {
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int size = 1;
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Node temp = head;
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while (temp.next != null) {
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temp = temp.next;
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size++;
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}
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return size;
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}
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}
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}
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