Add C_UniqueEmailAddresses.java

Author: ZahidFKhan

src/test/java/com/github/streams/practice/a_easy/numbers/EasyNumbersProblemSolution.java

@@ -101,4 +101,8 @@ public static long countNumberOfEvenNumbers(final List<Integer> input) {
   public static List<Double> convertCelsiusToFahrenheit(final List<Integer> input) {
     return input.stream().map(value -> (value * 9.0 / 5.0) + 32).toList();
   }
+
+    public static List<String> uniqueEmailAddresses(List<String> input) {
+      return input.stream().distinct().toList();
+    }
 }

src/test/java/com/github/streams/practice/a_easy/numbers/problems/C_SumOfDigits.java

@@ -0,0 +1,30 @@
+package com.github.streams.practice.a_easy.numbers.problems;
+
+import com.github.streams.practice.a_easy.numbers.EasyNumbersProblemSolution;
+import java.util.List;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+/**
+ * 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.
+ */
+class C_UniqueEmailAddresses {
+  @Test
+  void uniqueEmailAddresses() {
+    final var input =
+        List.of(
+            "[email protected]",
+            "[email protected]",
+            "[email protected]", // duplicate
+            "[email protected]",
+            "[email protected]" // duplicate
+            );
+
+    final var mySolution = EasyNumbersProblemSolution.uniqueEmailAddresses(input);
+    final var yourSolution = List.of();
+
+    Assertions.assertEquals(mySolution, yourSolution);
+  }
+}