Update MiddleOfLinkedList.java

Author: AYAZ2006

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

@@ -1,33 +1,58 @@
 package com.thealgorithms.datastructures.lists;
 
-// Definition for singly-linked list node
-public class ListNode {
-    public int val; // Value stored in the node
-    public ListNode next; // Pointer to the next node
-
-    public ListNode(int val) {
-        this.val = val;
-        this.next = null;
+/**
+ * Class to find the middle node of a singly-linked list.
+ */
+public class MiddleOfLinkedList {
+
+    /**
+     * Definition for singly-linked list node.
+     * Package-private class so it can be used internally.
+     */
+    static class ListNode {
+        int val; // Value stored in the node
+        ListNode next; // Pointer to the next node
+
+        /**
+         * Constructor to initialize a node with a value.
+         *
+         * @param val Value to store in the node.
+         */
+        ListNode(int val) {
+            this.val = val;
+            this.next = null;
+        }
     }
-}
 
-public class MiddleOfLinkedList {
+    /**
+     * Finds the middle node of a singly linked list.
+     * If there are two middle nodes, returns the second one.
+     *
+     * @param head Head node of the linked list.
+     * @return Middle node of the list.
+     */
     public ListNode middleNode(ListNode head) {
         if (head == null) {
             return head;
         }
 
-        ListNode slow = head;
-        ListNode fast = head;
+        ListNode slow = head; // moves one step at a time
+        ListNode fast = head; // moves two steps at a time
 
         while (fast != null && fast.next != null) {
-            slow = slow.next;
-            fast = fast.next.next;
+            slow = slow.next; // move slow by one node
+            fast = fast.next.next; // move fast by two nodes
         }
 
         return slow;
     }
 
+    /**
+     * Helper method to create a linked list from an array.
+     *
+     * @param values Array of integer values.
+     * @return Head node of the created linked list.
+     */
     public static ListNode createList(int[] values) {
         if (values.length == 0) {
             return null;
@@ -44,10 +69,15 @@ public static ListNode createList(int[] values) {
         return head;
     }
 
+    /**
+     * Helper method to print the linked list starting from any node.
+     *
+     * @param node Starting node to print from.
+     */
     public static void printList(ListNode node) {
         while (node != null) {
-            System.out.print(node.val + " ");
-            node = node.next;
+            System.out.print(node.val + " "); // print current node value
+            node = node.next; // move to next node
         }
         System.out.println();
     }