Migrate recursive reverse string method and tests to ReverseString (#6504)

* Migrate recursive reverse string method and tests to ReverseString

- Moved recursive reverse method from ReverseStringRecursive.java to ReverseString.java
- Moved tests from ReverseStringRecursiveTest.java to ReverseStringTest.java
- Deleted old ReverseStringRecursive files

* Fix formatting for ReverseStringTest.java as per clang-format linter

Author: ai-nihar

src/main/java/com/thealgorithms/strings/ReverseString.java

@@ -86,4 +86,17 @@ public static String reverseStringUsingStack(String str) {
         }
         return reversedString.toString();
     }
+
+    /**
+     * Reverse the String using Recursion
+     * @param str string to be reversed
+     * @return reversed string
+     */
+    public static String reverseStringUsingRecursion(String str) {
+        if (str.isEmpty()) {
+            return str;
+        } else {
+            return reverseStringUsingRecursion(str.substring(1)) + str.charAt(0);
+        }
+    }
 }

src/main/java/com/thealgorithms/strings/ReverseStringRecursive.java

@@ -7,6 +7,7 @@
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.CsvSource;
 import org.junit.jupiter.params.provider.MethodSource;
 
 public class ReverseStringTest {
@@ -44,4 +45,12 @@ public void testReverseStringUsingStack(String input, String expectedOutput) {
     public void testReverseStringUsingStackWithNullInput() {
         assertThrows(IllegalArgumentException.class, () -> ReverseString.reverseStringUsingStack(null));
     }
+
+    @ParameterizedTest
+    @CsvSource({"'Hello World', 'dlroW olleH'", "'helloworld', 'dlrowolleh'", "'123456789', '987654321'", "'', ''", "'A', 'A'", "'!123 ABC xyz!', '!zyx CBA 321!'", "'Abc 123 Xyz', 'zyX 321 cbA'", "'12.34,56;78:90', '09:87;65,43.21'", "'abcdEFGHiJKL', 'LKJiHGFEdcba'",
+        "'MixOf123AndText!', '!txeTdnA321fOxiM'"})
+    public void
+    testReverseStringUsingRecursion(String input, String expectedOutput) {
+        assertEquals(expectedOutput, ReverseString.reverseStringUsingRecursion(input));
+    }
 }