LinkedList_isPalindrome.java

import java.util.Stack;

public class LinkedList_isPalindrome {

    public static class Node {
        public int val;
        public Node next;

        // constructor
        public Node(int val) {
            this.val = val;
        }

        // for print
        @Override
        public String toString() {
            return Integer.toString(val);
        }
    }

    public static boolean isPalindrome1(Node head) {
        if (head == null) {
            return false;
        }

        Stack<Node> stack = new Stack<>();
        Node cur = head;
        while (cur != null) {
            stack.push(cur);
            cur = cur.next;
        }
        while (head.next != null) {
            if (head.val != stack.pop().val)
                return false;
            head = head.next;
        }
        return true;
    }

    public static void printLinkedList(Node head) {
        while (head.next != null) {
            System.out.print(head.val + "->");
            head = head.next;
        }
        System.out.print(head.val + "->");//for the last one
    }

    public static void main(String[] args) {
        Node node1 = new Node(1);
        node1.next = new Node(2);
        node1.next.next = new Node(2);
        node1.next.next.next = new Node(1);
        System.out.println(isPalindrome1(node1));

        Node node2 = new Node(1);
        node2.next = new Node(2);
        node2.next.next = new Node(3);
        System.out.println(isPalindrome1(node2));

    }
}