Question

Java

Write a pseudocode and Java program to implement the Stack using arrays. Write Push(), Pop(),and Display() methods to demonstrate that it works.

Answer 1

pseudocode:

procedure push(int x, stack[])
{
   if top == max_size_of_stack-1
   {
       display overflow
       return
   }
   else
   {
       top = top+1
       stack[top] = x
   }
   return
}

procedure pop(stack[])
{
   if top == -1
   {
       dispaly underflow
       return
   }

   else
   {
       top = top-1
       return stack[top]
   }
}

procedure display(stack[])
{
   if top == -1
   {
       display empty
       return
   }
   else
   {
       for i=top..0
       {
           print stack[i]
       }
   }
}

Source Code:

import java.util.*;

class Stack
{
   private int arr[];
   private int top;
   private int size;

   // Stack Constructor
   Stack(int size)
   {
       arr = new int[size];
       this.size = size;
       top = -1;
   }

   // pushes data x on to the stack
   public void push(int x)
   {

       // if stack is full exit
       if (top == size - 1)
       {
           System.out.println("Stack Overflow");
           return;
       }

       System.out.println(x + " Pushed!");
       // else push the data on to the stack
       arr[++top] = x;
   }

   // pops element from the stack
   public int pop()
   {
       // if stack is empty
       if (top == -1)
       {
           System.out.println("Stack Underflow!");
           return -1;
       }

       System.out.println(arr[top] + " popped!");

       // return the top of the array and decrement the top value
       return arr[top--];
   }

   // displays the content of the stack
   public void display()
   {
       if(top == -1)
       {
           System.out.println("Stack is Empty");
           return;
       }
       // dispalays stack in the format as the stack
       for(int i=top; i>=0; i--)
       {
           System.out.println(arr[i]);
       }
   }

   public static void main (String[] args)
   {

        // size of stack is 5
       Stack stack = new Stack(5);

       System.out.println("Pushing data!!");
       stack.push(1);       // pushing 1 on to stack
       stack.push(2);       // pushing 2 on to stack
       stack.push(3);       // pushing 3 on to stack
       stack.push(4);       // pushing 4 on to stack

       System.out.println("\nAfter pushing elements onto stack: ");
       stack.display();

       System.out.println("\nPopping data!!");
       stack.pop();       // removing the top 2
       stack.pop();       // removing the top 1

       System.out.println("\nContents Of stack after all operations: ");
       stack.display();
   }
}

Output:

Pushing data!! 1 Pushed! 2 Pushed! 3 Pushed! 4 Pushed! After pushing elements onto stack: Popping data!! 4 popped! 3 popped! Contents of stack after all operations: PN

if size of stack is 1

Pushing data!! 1 Pushed! Stack Overflow Stack Overflow Stack Overflow After pushing elements onto stack: Popping data!! 1 popped! Stack Underflow! Contents of stack after all operations: Stack is Empty

Hope your problem solved and appreciating this solution.

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