docs(easy-problems): add class-level JavaDoc with description and input/output examples

All easy problem test classes under a_easy_problems/numbers and
a_easy_problems/strings now have a consistent class-level JavaDoc comment
describing the problem and showing a concrete example with Input, Output,
and where useful an Explanation line.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: ZahidFKhan

src/test/java/com/github/streams/practice/a_easy_problems/numbers/B_MapCelsiusToFahrenheit.java

@@ -11,6 +11,9 @@
  * F = (C * 9/5) + 32.
  * This requires using the map function to transform each element and ensure the result is collected into
  * a List<Double>.
+ * <p>Example: <br>
+ * Input: [0, 10, 25, 37, 100] <br>
+ * Output: [32.0, 50.0, 77.0, 98.6, 212.0]
  */
 class B_MapCelsiusToFahrenheit {
 

src/test/java/com/github/streams/practice/a_easy_problems/numbers/C_UniqueEmailAddresses.java

@@ -7,8 +7,13 @@
 
 /**
  * Imagine you’re building a registration system for a website. Sometimes, due to user error or
- * system retries, duplicate emails get stored in your list.
- * You want to keep only unique email addresses before sending a newsletter.
+ * system retries, duplicate emails get stored in your list. You want to keep only unique email
+ * addresses before sending a newsletter.
+ *
+ * <p>Example: <br>
+ * Input: ["john.doe@example.com", "alice@example.com", "john.doe@example.com",
+ * "bob@example.com", "alice@example.com"] <br>
+ * Output: ["john.doe@example.com", "alice@example.com", "bob@example.com"]
  */
 class C_UniqueEmailAddresses {
   @Test

src/test/java/com/github/streams/practice/a_easy_problems/numbers/G_DescendingNumberValue.java

@@ -5,12 +5,14 @@
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
-/*
- * Given a numeric array , re arrange the elements to form a highest possible value.
- * Input:  {1, 34, 3, 98, 9, 76, 45, 4};
- * Output: 998764543431
- * Explanation: 9,98,76,45,4,34,3,1
- * */
+/**
+ * Re-arranges the elements of a numeric array to form the highest possible value.
+ *
+ * <p>Example: <br>
+ * Input: [1, 34, 3, 98, 9, 76, 45, 4] <br>
+ * Output: "998764543431" <br>
+ * Explanation: Numbers re-arranged as 9, 98, 76, 45, 4, 34, 3, 1.
+ */
 class G_DescendingNumberValue {
 
   @Test

src/test/java/com/github/streams/practice/a_easy_problems/numbers/H_ReverseANumber.java

@@ -5,6 +5,13 @@
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
+/**
+ * Reverse the digits of an integer.
+ *
+ * <p>Example: <br>
+ * Input: 12345 <br>
+ * Output: 54321
+ */
 class H_ReverseANumber {
 
   @Test

src/test/java/com/github/streams/practice/a_easy_problems/numbers/J_MeanOfNumbers.java

@@ -5,6 +5,13 @@
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
+/**
+ * Calculate the mean (average) of a list of integers.
+ *
+ * <p>Example: <br>
+ * Input: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20] <br>
+ * Output: 10.5
+ */
 class J_MeanOfNumbers {
   @Test
   @Disabled

src/test/java/com/github/streams/practice/a_easy_problems/numbers/K_IntArray2DToListConverter.java

@@ -6,6 +6,13 @@
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
+/**
+ * Convert a 2D integer array into a List of Lists of Integers using streams.
+ *
+ * <p>Example: <br>
+ * Input: {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}} <br>
+ * Output: [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
+ */
 public class K_IntArray2DToListConverter {
   @Test
   @Disabled

src/test/java/com/github/streams/practice/a_easy_problems/strings/C_LengthOfCityTest.java

@@ -8,17 +8,13 @@
 import org.junit.jupiter.api.Test;
 
 /**
- * Calculates the length of city names that start with 'm' or 'M'. <br>
- * <br>
+ * Calculates the length of city names that start with 'm' or 'M' and returns a map of city name
+ * to its length.
  *
- * <h3>Example Cities</h3>
- *
- * <ul>
- *   <li>Mumbai
- *   <li>Munnar
- *   <li>Chennai
- *   <li>Hyderabad
- * </ul>
+ * <p>Example: <br>
+ * Input: ["Mumbai", "Munnar", "Chennai", "Hyderabad"] <br>
+ * Output: {"Mumbai"=6, "Munnar"=6} <br>
+ * Explanation: Only cities starting with 'M' or 'm' are included.
  */
 class C_LengthOfCityTest {
   @Test

src/test/java/com/github/streams/practice/a_easy_problems/strings/D_NumberOfOccurencesOfEachCharacterTest.java

@@ -6,6 +6,14 @@
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
+/**
+ * Count the number of occurrences of each character in a string (spaces excluded).
+ *
+ * <p>Example: <br>
+ * Input: "the quick brown fox jumps right over the little lazy dog little" <br>
+ * Output: {'t'=5, 'h'=3, 'e'=5, 'q'=1, 'u'=2, ...} <br>
+ * Explanation: Each character is mapped to how many times it appears in the string.
+ */
 class D_NumberOfOccurencesOfEachCharacterTest {
   @Test
   @Disabled("Remove This Once you Complete The Exercise")

src/test/java/com/github/streams/practice/a_easy_problems/strings/E_NumberOfOccurencesOfEachWordTest.java

@@ -6,6 +6,14 @@
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
+/**
+ * Count the number of occurrences of each word in a string.
+ *
+ * <p>Example: <br>
+ * Input: "the quick brown fox jumps right over the little lazy dog little" <br>
+ * Output: {"the"=2, "little"=2, "quick"=1, "brown"=1, ...} <br>
+ * Explanation: Each word is mapped to how many times it appears in the string.
+ */
 class E_NumberOfOccurencesOfEachWordTest {
   @Test
   @Disabled

src/test/java/com/github/streams/practice/a_easy_problems/strings/F_ConcatenationOfStrings.java

@@ -5,11 +5,15 @@
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
+/**
+ * Given a list of strings, concatenate all strings separated by a comma using Java Streams.
+ *
+ * <p>Example: <br>
+ * Input: ["Hellow", "World", "Hello", "World"] <br>
+ * Output: "Hellow,World,Hello,World"
+ */
 class F_ConcatenationOfStrings {
-  /**
-   * Given a list of strings, write a method to concatenate all the strings in the list, separated
-   * by a comma, using Java 8 Streams.
-   */
+
   @Test
   @Disabled
   void testConcatenationOfStrings() {