feat(CodeChefDemo): add simple ArrayList demo with remove operation

What
- Added CodeChefDemo class.
- Created an ArrayList<Integer>.
- Added elements [12, 25, 34, 46].
- Removed element at index 1 (value = 25).
- Stored removed value in variable RemoveANumber.
- Printed the removed number and the final list.

Why
- Demonstrates ArrayList usage for basic insertion and deletion.
- Shows difference between remove(int index) and remove(Object o).
- Provides clear output verifying which element was removed and what remains in the list.

How
- list.add(...) → list = [12,25,34,46].
- list.remove(1) → removes index 1 element (25), returns it.
- After removal → list = [12,34,46].
- Print removed number and final list.

Logic
- Inputs: integers added to list.
- Outputs:
  - Removed number = 25.
  - Final list = [12,34,46].
- Flow:
  1. Initialize empty ArrayList.
  2. Add four integers.
  3. Remove element at index 1.
  4. Print removed element and final list.
- Edge cases:
  - If index out of range, throws IndexOutOfBoundsException.
  - If remove(Object) were used instead, it would remove the first matching occurrence.
- Complexity:
  - add(E): amortized O(1).
  - remove(index): O(n) due to element shifting.
- Concurrency: ArrayList not thread-safe.

Real-life applications
- Managing dynamic lists where elements are frequently added/removed.
- Handling user-selected item deletions in apps.
- Useful exercise to understand remove() overload behavior.

Notes
- remove(int index) vs remove(Object o):
  - remove(1) → removes element at index 1.
  - remove(Integer.valueOf(25)) → removes element with value 25.
- In this example, both approaches work since we know 25 is at index 1.

Signed-off-by: https://github.com/Someshdiwan <[email protected]>

Author: Someshdiwan

Section25CollectionFramework/src/ListDemo/ArrayListLinkedListStack/CodeChecf.java renamed to Section 25 Collections Frameworks/List Interface/ArrayList/src/CodeChefDemo.java

@@ -1,14 +1,14 @@
-package ListDemo.ArrayListLinkedListStack;
-/*
-Write a program that does the following.
+/* Write a program that does the following.
 
-Create an ArrayList of integers, add the elements [12, 25, 34, 46] to it Remove the number 25 from the ArrayList
+Create an ArrayList of integers, add the elements [12, 25, 34, 46]
+to it Remove the number 25 from the ArrayList.
 
 Print the final ArrayList.
 */
+
 import java.util.*;
 
-class CodeChef {
+class CodeChefDemo {
     public static void main(String[] args) {
         ArrayList<Integer> list = new ArrayList<>();
         list.add(12);
@@ -17,7 +17,7 @@ public static void main(String[] args) {
         list.add(46);
 
         Integer RemoveANumber = list.remove(1);
-        System.out.println("Number to be removed: "+RemoveANumber);
-        System.out.println("Final List: "+list);
+        System.out.println("Number to be removed: "+ RemoveANumber);
+        System.out.println("Final List: " + list);
     }
-}
+}