Check the content of linked list is palindrome

Question: Check the content of singly linked list is palindrome or not. 

Example: 

Input:  1 -> 2-> 3->4->3->2->1

Output: True

Input: 1 -> 2-> 3->4->5->2->1

Output: False

Solution:

 public boolean isPalindrome(ListNode head) {
       
        ListNode slow, fast;
        slow=fast=head;
        ListNode prev = null;
        while(fast!=null && fast.next!=null) {
            ListNode next = slow.next;
            fast = fast.next.next;
            slow.next = prev;
            prev = slow;
            slow = next;
        }
        if(fast!=null){
            slow = slow.next;
        }
     
        while(slow != null) {
            if(slow.val != prev.val) {
                return false;
            }
            slow = slow.next;
            prev = prev.next;
        }
        return true;

    }

Solution 2: Using Stack

      /**

        * Check the content of linked list is palindrome or not

        *

        * @param l

        * @return

        */

       public boolean Palindrome(ListNode head)

       {

              if(l==null){

                     System.out.println("Empty List");

                     return false;

              }

              else {

                     Stack<ListNode> stack = new Stack<ListNode>();

                     ListNode slow, fast;

                     slow=fast=head;              

                     // add first half of list to stack with help of slow and fast pointers

                     while(slow!=null && fast!=null && fast.next!=null) {

                           // add to stack

                           stack.add(slow);

                           // increment slow pointer one node at a time

                           slow=slow.next;

                           // increment fast pointer two nodes at a time

                           fast=fast.next.next;

                     }     

                     // add to the stack if fast.next is null to cover odd number of nodes case

                     if(fast!=null && fast.next==null) {

                           stack.add(slow);    

                     }

                     // Compare second half of list with stack values which contains first half of list

                     while(!stack.isEmpty()) {

                           // pop the node from stack

                           ListNode temp = stack.pop();

                           // check both the node values

                           if(slow.element != temp.element) {

                                  return false;

                           }

                           // increment slow pointer by one node

                           slow=slow.next;

                     }

                     // return as palindrome if all the nodes matches

                     return true;              

              }            

       }