题解 | #反转链表#

/*
public class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}*/
public class Solution {
    public ListNode ReverseList(ListNode head) {
      if(head==null||head.next==null){
          return head;
      }
       ListNode pre = null;
        ListNode next =null;
        while(head!=null){
            next =head.next;
            head.next=pre;
            pre =head;
            head= next;
        }
        return pre;
    }
}