leetcode[206] Reverse Linked Lis

题目要求

Reverse a singly linked list.

实现思路

通过头插法新建一个链表并将其返回

代码

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    
    public ListNode reverseList(ListNode head) {
        ListNode node1= null;
        ListNode tmp = head;
        while(tmp!= null){
            if(node1 == null){
                ListNode newNode = new ListNode(tmp.val);
                node1 = newNode;
                node1.next = null;
                
            }else{
                ListNode newNode = new ListNode(tmp.val);
                newNode.next = node1;
                node1 = newNode;
            }
            tmp = tmp.next;
        }
        return node1;
        
    }
}