2018-11-07

class Solution {
    public ListNode reverseList(ListNode head) {
        ListNode current = head;
        ListNode pre = null;
        
        ListNode newHead = null;
        while(current != null){
            ListNode next = current.next;
            if (next == null) {
                newHead = current;
            }
            current.next = pre;
            pre = current;
            current = next;
        }
        return newHead;
    }
}