Stack

Problem Statement: 
        Implement Stack

Solution:

Stack supports three main operations:
1. Push:
         Insertion of element
2. Pop:
       Removal of the last element inserted
3. Peek:
 
A stack supports LIFO operations i.e. Last In First Out (LIFO)
These all operations are assisted by the "top" pointer which tracks the top most element element in the stack. 

Fig: Stack of books and Stack of Boxes

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-  /**  * Stack Implementation  * @author Prateek Rathore  *  */ public class Stack {  int arr[];  private static final int DEFAULT_CAPACITY = 10;  public static int top = -1;     public Stack() {   arr = new int[DEFAULT_CAPACITY];  }     public Stack(int size) {   arr = new int[size];  }    public void push(int data) {   arr[++top] = data;  }  public int pop() {   return arr[top--];  }    public int peek() {            return arr[top];  }     public boolean isEmpty() {   if(top==-1)    return true;   return false;  } } -

References:
   Refer to one of my friend's post on stacks: LINK
               
Please post your comments and suggestions.

Happy Coding !! :)