Added stack for java. 3 ways to create a stack in java using array, q…

[attu0]

This pull request adds three different implementations of a stack data structure in Java, each demonstrating a unique approach: using an array, using a linked list, and using a queue. These examples provide a clear comparison of stack operations across various underlying data structures.

Stack implementations:

• Array-based stack: Introduced a stack class in UsingArray.java that uses a fixed-size array to implement standard stack operations (push, pop, top, and size). Includes a main method with sample usage.
• Linked list-based stack: Added a Stack class in UsingLinkedList.java using a singly linked list for dynamic stack operations, including push, pop, peek, isEmpty, and display. Includes a Node helper class and a main method for demonstration.
• Queue-based stack: Implemented a stack in UsingQueue.java using a single queue (LinkedList) to simulate stack behavior, with logic in push to maintain LIFO order. Includes standard stack methods and a main method for example usage.…ueue and LinkedList

[github-actions]

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[github-actions]

🤖 Automated PR Status

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✅ Passed - File naming and structure look good!

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✅ Passed - All code compiles successfully!

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[admirerr]

Approved