public static boolean isPail (ListNode head) { List<integer> list = new ArrayList(); if(head ==null|| head.next==null) return true; while (head != null) { list.add(head.val); head = head.next; } int i; int j; for( i=0, j=list.size()-1;i<=j;i++,j--){ if(list.get(i)!=list.get(j)){ return false; } } return true; 这样错在哪了</integer>