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) {
        //特殊情况判断
        if(head == null){
            return null;
        }

        //依次反转当前节点，直到当前节点为空时，返回前一个节点。
        ListNode pre = null, cur = head;
        while(cur != null){
            ListNode tmp = cur.next;
            cur.next = pre;
            pre = cur;
            cur = tmp;
        }

        return pre;
    }
}