非递归实现

public class Simple206 {
    public ListNode reverseList(ListNode head) {
        ListNode pre =null;
        ListNode cur =head;
        while(cur.next !=null){
            ListNode next = cur.next;
            cur.next = pre;
            pre = cur;
            cur = next;
        }
        cur.next = pre;
        return cur;
    }
}