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[Solved] Easy methods to reverse a Stack in Java utilizing Recursion and Iteration? Instance Tutorial

Hiya guys, in case you are questioning how one can reveres a stack in Java then do not go
wherever. On this article, I’ll present you step-by-step
how one can reverse a given stack in Java
. There are two methods to reverse a stack, you should use
iteration or
recursion. The commonest approach of reversing a stack is to make use of an auxiliary stack. First,
we are going to pop all the weather from the stack and push them into the auxiliary
stack. As soon as all the weather are pushed into the auxiliary stack, then it
accommodates the weather within the reverse order and we merely print them. However, right here,
we won’t use the auxiliary stack. We are going to use a recursion methodology to reverse a
stack the place
means calling the operate itself repeatedly. 
What do I imply by auxiliary stack? Auxiliary information construction is a candy
approach of claiming helper information construction. One thing you would possibly use to unravel a given
drawback and is terminated after the issue is solved.

For instance,
if I requested you to seek out the rely of every component I’ve in an
array. A technique to do that is by utilizing a hash desk(key-value pairs). You’ll retailer
the weather within the desk as keys and their occurrences as values. 

Then you possibly can traverse the desk and discover the occurrences of every component.
After you get the occurrences you would not want the desk, subsequently, it is an
auxiliary information construction. Taking over further area for a short lived interval of

Within the recursion methodology, we first pop all the weather from the enter stack
and push all of the popped objects into the operate name stack till the stack
turns into empty. When the stack turns into empty, all of the objects might be pushed at
the stack. 

Btw, that is additionally one of many frequent stack coding issues from Java interviews and in case you want extra stack questions then you may also examine that

Easy methods to reverse a Stack in Java utilizing Recursion? Code Instance

Stack is a linear information construction much like arrays and linked lists that permit us to retailer and
retrieve information sequentially. Generally, insertion operation is
known as 
“push,” and deletion operation is known as “pop.” They’re helpful when dynamic addition and deletion of parts are

At any given time, one can solely entry the highest component of a stack.
Attributable to this motive, it’s a 
LIFO (Final In First Out) information construction. On this, the component added final is accessed first. The time
complexity for all operations in a stack is 
O(1), making it environment friendly and enhancing efficiency.

Stack information construction, the final merchandise is the primary to get out because it has been stated above. Suppose
of plates that you simply place on themselves after washing. Yeah! That’s
precisely the stack information construction. It makes no logical sense to deliver out
the primary merchandise that acquired in out first,

You doing which means you’re out of stack information construction, you’re already
going into one other sort of information construction. Right here, we need to
reverse a stack. Think about that you’ve got numbers 1 – 10 saved in a stack, now we need to
implement it to be saved the opposite approach spherical which suggests 10 – 1, lets

public class StackReversion {
  static Stack < Character > stack = new Stack < > ();
  static void insert_at_bottom(char x) {
    if (stack.isEmpty())
    else {
      char a = stack.peek();
  static void reverse() {
    if (stack.measurement() > 0) {
      char x = st.peek();
  // Driver Code 
  public static void fundamental(String[] args) {
    System.out.println("Authentic Stack");
    System.out.println("Reversed Stack");

Clarification of Resolution and Code

Class declaration in line 1 and Stack was launched in line 2, which takes
in character as a sort. Word: as a result of the
can’t maintain primitive sorts it must be auto-boxed to reference sorts that
is why the character was a capital letter, with a variable title stack which
was initialized to the brand new stack.

In line 3, the tactic
“insertFromBottom” was created that takes in a parameter of character sort,
so if the stack is empty, it ought to push within the parameter, but when not it
ought to proceed to hold out the remainder of the codes. So line 19 executes by
peeking on the merchandise on the high and saving in a variable. 

After the peek methodology was known as then the tactic reverse was known as.

So, the implementation of the tactic “reverse” goes thus: line 15, the
methodology “reverse” was created which returns void. So, if the scale of the
stack is bigger than zero then the peek methodology could be known as and saved
inside variable then, after that, the pop methodology does it work too to come out
the component, and after that was a recursion name. 

This retains taking place till it reaches the tip of the stack. After every
recursion name, the tactic “insertFromBottom” is all the time known as.

reverse a stack using recursion and iteration in Java
Driver class:
The primary methodology was declared in line
26. from traces 28 to 31, 4 completely different objects have been pushed into the stack,
1,2,3,4 respectively. Line 33 and 35 print the unique stack after which
the reverse() methodology was known as,
then the reversed stack was printed.


Authentic Stack:

Reversed Stack:


That is all about how one can reverse a Stack in Java. This isn’t solely a
good train to study Stack but additionally to study recursion and
how one can convert an iterative answer to recursion one utilizing the
acceptable information construction. 

Stack is without doubt one of the vital information constructions and I imagine each
programmer ought to find out about it and be accustomed to its properties. I
principally use stack to transform interactive algorithms to a recursion one like
on this instance. You probably have any questions with respect to this answer
or rationalization be happy to ask. 

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Thanks for studying this coding drawback answer up to now. When you like this
article, then please share it with your folks and colleagues. When you
have any questions or doubt then please tell us and I am going to attempt to discover
a solution for you. As all the time ideas, feedback, revolutionary and higher
solutions are most welcome.

P. S. – If you wish to enhance your DSA abilities and wish the very best
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