codeIIEST/Algorithms

package Data_Structures
import java.util.*;
class stack
{ //Begin class

    int top = -1, size, s[];
    
    
    /*****Constructor to initialise the stack *****/
    stack(int n)
    { //Begin constructor
        size = n;
        
        s = new int[size];        
        for(int i = 0; i < size; i++)
        { //Begin for
            s[i] = 0;
        } //End for            
    } //End constructor
        
        
        
    /***** Fucntion to insert/push item to stack *****/
    private void push(int item)
    { //Begin push()
    
        if(top == (size-1)) //Checks if stack is full
        { //Begin if
            System.out.println("Stack overflow");
        } //End if
        
        else //Element is entered to the stack when there is place
        { //Begin else
            top++;
            s[top] = item;
        } //End else
        
    } //End push()
    
    
    
    /***** Function to delete/pop an item (topmost element) from stack *****/
    private void pop()
    { //Begin pop()
        
        if(top == -1) //Checks if stack is empty
        { //Begin if
            System.out.println("Stack underflow");
        } //End if
        
        else
        { //Begin else
            System.out.println("Item deleted is:\t"+s[top]);
            top--;
        } //End else
    } //End pop()
    
    
    /***** Function to peep (show the topmost element in stack) *****/
    private void peep()
    { //Begin peep()
        if(top == -1)
            System.out.println("No element to peep");
        
        else
            System.out.println("Peep: top ---> "+s[top]);
    } //End peep()
    
    
    
    /***** Function to display the elements of stack *****/
    private void display()
    { //Begin display()
                
        if(top == -1)
        { //Begin if
            System.out.println("No elements in stack");
        } //End if
        
        else
        { //Begin else
            
            System.out.print("Elements of the stack: top---> ");
            for(int i=top; i>=0; i--)
            {
                System.out.print(s[i]+"\t");
            }
            System.out.println();
        } //End else
    } //End display()
    
    
    /***** main fucntion *****/
    public static void main(String args[])
    { //Begin main()
    
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter the size of the stack");
        int n = sc.nextInt();
        
        stack st = new stack(n);
        
        int choice;
        do
        { //Begin do
            System.out.println("\nEnter:\n1. Push\n2. Pop\n3. Peep\n4. Display");
            choice = sc.nextInt();
            switch(choice)
            { //Begin switch
                case 1: System.out.println("\nEnter an element to push");
                    int element = sc.nextInt();
                    st.push(element);
                    break;
                    
                case 2: st.pop();
                    break;
                    
                case 3: st.peep();
                    break;
                
                case 4: st.display();
                    break;
                    
                default: System.out.println("Wrong choice. Exitting!");
                    break;
            } //End switch
        } //End do
        while(choice >= 1 && choice <= 4);
    } //End main()
} //End class