题解 | #反转链表#

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

    ListNode(int val) {
        this.val = val;
    }
}*/
/**
先确定 head, next位置， 断开lianjie3
*/
public class Solution {
    public ListNode ReverseList(ListNode head) {
        if (head == null) {
            return null;
        }
        ListNode next = head.next;
        if (next == null) {
            return head;
        }
        head.next = null;
        ListNode cur = null;
        while ( next != null) {
            cur = next;
            next = next.next;
            cur.next = head;
            head = cur;
        }
        return head;
    }

}