Add FindMiddleNode algorithm with ListNode class and JUnit tests

Author: MedhaSunkad13

src/main/java/com/thealgorithms/datastructures/lists/FindMiddleNode.java

@@ -1,6 +1,10 @@
 package com.thealgorithms.datastructures.lists;
 
-public class FindMiddleNode {
+public final class FindMiddleNode {
+
+    private FindMiddleNode() {
+        throw new UnsupportedOperationException("Utility class");
+    }
 
     public static ListNode findMiddle(ListNode head) {
         ListNode slow = head;
@@ -24,4 +28,3 @@ public static void main(String[] args) {
         System.out.println("Middle node value: " + middle.value);
     }
 }
-// package com.thealgorithms.datastructures.lists;

src/test/java/com/thealgorithms/datastructures/lists/FindMiddleNodeTest.java

@@ -7,13 +7,13 @@ public class FindMiddleNodeTest {
 
     @Test
     public void testOddLengthList() {
-        ListNode head = createList(new int[]{1, 2, 3, 4, 5});
+        ListNode head = createList(new int[] { 1, 2, 3, 4, 5 });
         assertEquals(3, FindMiddleNode.findMiddle(head).value);
     }
 
     @Test
     public void testEvenLengthList() {
-        ListNode head = createList(new int[]{1, 2, 3, 4, 5, 6});
+        ListNode head = createList(new int[] { 1, 2, 3, 4, 5, 6 });
         assertEquals(4, FindMiddleNode.findMiddle(head).value);
     }
 
@@ -27,4 +27,3 @@ private ListNode createList(int[] values) {
         return head;
     }
 }
-