palindrome

	public boolean isPalindrome(ListNode head){
		if(head == null || head.next == null) return true;
		Stack<Integer> s = new Stack<Integer>();
		ListNode slow = head;
		ListNode fast = head;
		while(fast.next != null){
			s.push(slow.data);
			slow = slow.next;
			fast = fast.next.next;
		}
		
		if(fast != null){
			slow = slow.next;
		}
		
		while(slow != null){
			int top = s.pop().intValue();
			if(top != slow.data) return false;
			slow = slow.next;
		}
		
		return true;
	}