feat(HashMapPractice2): implement simple hash function demo using ASCII sum modulo

What
- Added `simpleHash(String key)` method to compute a basic hash:
  - Iterates over each character in the string.
  - Sums ASCII values of all characters.
  - Returns `sum % 10` as the hash.
- Demonstrated with `"ABC"` and `"CBA"` producing identical hash values.

Why
- To illustrate how custom/simple hash functions work.
- Shows that strings with the same character set in different orders can collide.
- Helps understand why real `HashMap` implementations use more complex hash algorithms.

How
1. `"ABC"` → ASCII: `65 + 66 + 67 = 198` → `198 % 10 = 8`.
2. `"CBA"` → ASCII: `67 + 66 + 65 = 198` → `198 % 10 = 8`.
3. Both map to the same bucket index `8` → **hash collision**.

Key Notes
- This simple hash function is **not good in practice**:
  - Different permutations of characters (e.g., `"ABC"`, `"CBA"`, `"BAC"`) will produce the same hash.
  - Leads to frequent collisions when used in a hash table.
- Java’s `HashMap` uses a much stronger hash spread function to reduce collisions.

Real-world takeaway
- Always use robust hashing strategies for keys.
- Simple modulo-based hashes are useful only for **teaching/demo** purposes, not production.

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

Author: Someshdiwan

Section25CollectionFramework/src/HashMapDemo/HashMapPractice2.java renamed to Section 25 Collections Frameworks/Map Interface/HashMap/src/HashMapPractice2.java

@@ -1,24 +1,18 @@
-package HashMapDemo;
-
 public class HashMapPractice2 {
     public static void main(String[] args) {
         System.out.println(simpleHash("ABC"));
         System.out.println(simpleHash("CBA"));
     }
-    public static int simpleHash(String key)
-    {
+
+    public static int simpleHash(String key) {
         int sum = 0;
-        for (char c : key.toCharArray()) // Convert string to char array and iterate
+        for (char c : key.toCharArray()) // Convert string to a char array and iterate
         {
             sum += (int) c; // Sum ASCII values of characters
         }
         return sum % 10; // Return sum modulo 10 as the hash
     }
 }
-/*
-"ABC" ? ASCII values: A (65) + B (66) + C (67) = 198
-198 % 10 = 8
 
-"CBA" ? ASCII values: C (67) + B (66) + A (65) = 198
-198 % 10 = 8
-*/
+// "ABC" ? ASCII values: A (65) + B (66) + C (67) = 198. 198 % 10 = 8
+// "CBA" ? ASCII values: C (67) + B (66) + A (65) = 198. 198 % 10 = 8