剑指offer-反转链表

 

题目描述

输入一个链表，反转链表后，输出新链表的表头。

 

 

题目链接：

https://www.nowcoder.com/practice/75e878df47f24fdc9dc3e400ec6058ca?tpId=13&tqId=11168&rp=1&ru=/activity/oj&qru=/ta/coding-interviews/question-ranking

 

 

 

 

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

    ListNode(int val) {
        this.val = val;
    }
}*/
public class Solution {
    public ListNode ReverseList(ListNode head) {
        if(null == head){
            return null;
        }
        //记录新链表的表头
        ListNode newHead = null;
        //记录旧链表的表头
        ListNode oldTail = head;
        while(oldTail != null){
            //存一下当前节点
            ListNode cur = oldTail;
            //旧链表下一个节点
            oldTail = oldTail.next;
            //当前节点指向新链表表头
            cur.next = newHead;
            //更新新链表表头
            newHead = cur;
        }
        
        return newHead;
    }
}