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) {
            return null;
        }
        if(head.next==null){
            return head;
        }
        ListNode pre = head;
        ListNode next = null;
        ListNode temp = pre.next;
        head.next = null;
        do {
            next = pre;
            pre = temp;
            temp = pre.next;
            pre.next = next;
        } while (temp != null);
        return pre;
    }
}