Code:
import java.util.*;
/* Class stackUsingQueue */
class stackUsingQueue
{
Queue
Queue
/* Constructor */
public stackUsingQueue()
{
q = new LinkedList
tmp = new LinkedList
}
/* Function to push an element to the stack */
public void push(int data)
{
/* if no element is present in queue q then
* enqueue the new element into q */
if (q.size() == 0)
q.add(data);
else
{
/* if elements are present in q then
* dequeue all the elements to
* temporary queue tmp */
int l = q.size();
for (int i = 0; i < l; i++)
tmp.add(q.remove());
/* enqueue the new element into q */
q.add(data);
/* dequeue all the elements from
* temporary queue tmp to q */
for (int i = 0; i < l; i++)
q.add(tmp.remove());
}
}
/* Function to remove top element from the stack */
public int pop()
{
if (q.size() == 0)
throw new NoSuchElementException("Underflow Exception");
return q.remove();
}
/* Function to check the top element of the stack */
public int peek()
{
if (q.size() == 0)
throw new NoSuchElementException("Underflow Exception");
return q.peek();
}
/* Function to check if stack is empty */
public boolean isEmpty()
{
return q.size() == 0 ;
}
/* Function to get the size of the stack */
public int getSize()
{
return q.size();
}
/* Function to display the status of the stack */
public void display()
{
System.out.print("\nStack = ");
int l = getSize();
if (l == 0)
System.out.print("Empty\n");
else
{
Iterator it = q.iterator();
while (it.hasNext())
System.out.print(it.next()+" ");
System.out.println();
}
}
}
/* Class StackImplementUsingTwoQueues */
public class StackImplementUsingTwoQueues
{
public static void main(String[] args)
{
Scanner scan = new Scanner(System.in);
stackUsingQueue suq = new stackUsingQueue();
/* Perform Stack Operations */
System.out.println("Stack Using Two Queues Test\n");
char ch;
do
{
System.out.println("\nStack Operations");
System.out.println("1. push");
System.out.println("2. pop");
System.out.println("3. peek");
System.out.println("4. check empty");
System.out.println("5. size");
int choice = scan.nextInt();
switch (choice)
{
case 1 :
System.out.println("Enter integer element to push");
suq.push( scan.nextInt() );
break;
case 2 :
try
{
System.out.println("Popped Element = "+ suq.pop() );
}
catch (Exception e)
{
System.out.println("Error : " + e.getMessage());
}
break;
case 3 :
try
{
System.out.println("Peek Element = "+ suq.peek() );
}
catch (Exception e)
{
System.out.println("Error : " + e.getMessage());
}
break;
case 4 :
System.out.println("Empty status = "+ suq.isEmpty() );
break;
case 5 :
System.out.println("Size = "+ suq.getSize() );
break;
default :
System.out.println("Wrong Entry \n ");
break;
}
/* Display Stack */
suq.display();
System.out.println("\nDo you want to continue (Type y or n) \n");
ch = scan.next().charAt(0);
} while (ch == 'Y'|| ch == 'y');
}
}
Output:
Stack Using Two Queues Test
Stack Operations
1. push
2. pop
3. peek
4. check empty
5. size
4
Empty status = true
Stack = Empty
Do you want to continue (Type y or n)
y
Stack Operations
1. push
2. pop
3. peek
4. check empty
5. size
1
Enter integer element to push
5
Stack = 5
Do you want to continue (Type y or n)
y
Stack Operations
1. push
2. pop
3. peek
4. check empty
5. size
1
Enter integer element to push
99
Stack = 99 5
Do you want to continue (Type y or n)
y
Stack Operations
1. push
2. pop
3. peek
4. check empty
5. size
1
Enter integer element to push
73
Stack = 73 99 5
Do you want to continue (Type y or n)
y
Stack Operations
1. push
2. pop
3. peek
4. check empty
5. size
1
Enter integer element to push
50
Stack = 50 73 99 5
Do you want to continue (Type y or n)
y
Stack Operations
1. push
2. pop
3. peek
4. check empty
5. size
1
Enter integer element to push
1
Stack = 1 50 73 99 5
Do you want to continue (Type y or n)
y
Stack Operations
1. push
2. pop
3. peek
4. check empty
5. size
1
Enter integer element to push
24
Stack = 24 1 50 73 99 5
Do you want to continue (Type y or n)
y
Stack Operations
1. push
2. pop
3. peek
4. check empty
5. size
5
Size = 6
Stack = 24 1 50 73 99 5
Do you want to continue (Type y or n)
y
Stack Operations
1. push
2. pop
3. peek
4. check empty
5. size
3
Peek Element = 24
Stack = 24 1 50 73 99 5
Do you want to continue (Type y or n)
y
Stack Operations
1. push
2. pop
3. peek
4. check empty
5. size
2
Popped Element = 24
Stack = 1 50 73 99 5
Do you want to continue (Type y or n)
y
Stack Operations
1. push
2. pop
3. peek
4. check empty
5. size
2
Popped Element = 1
Stack = 50 73 99 5
Do you want to continue (Type y or n)
y
Stack Operations
1. push
2. pop
3. peek
4. check empty
5. size
2
Popped Element = 50
Stack = 73 99 5
Do you want to continue (Type y or n)
y
Stack Operations
1. push
2. pop
3. peek
4. check empty
5. size
2
Popped Element = 73
Stack = 99 5
Do you want to continue (Type y or n)
y
Stack Operations
1. push
2. pop
3. peek
4. check empty
5. size
1
Enter integer element to push
2
Stack = 2 99 5
Do you want to continue (Type y or n)
y
Stack Operations
1. push
2. pop
3. peek
4. check empty
5. size
2
Popped Element = 2
Stack = 99 5
Do you want to continue (Type y or n)
y
Stack Operations
1. push
2. pop
3. peek
4. check empty
5. size
2
Popped Element = 99
Stack = 5
Do you want to continue (Type y or n)
y
Stack Operations
1. push
2. pop
3. peek
4. check empty
5. size
2
Popped Element = 5
Stack = Empty
Do you want to continue (Type y or n)
y
Stack Operations
1. push
2. pop
3. peek
4. check empty
5. size
3
Error : Underflow Exception
Stack = Empty
Do you want to continue (Type y or n)
y
Stack Operations
1. push
2. pop
3. peek
4. check empty
5. size
4
Empty status = true
Stack = Empty
Do you want to continue (Type y or n)
n
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