leetcode206~Reverse Linked List

Reverse a singly linked list

public class ReverseLinkedList {    public ListNode reverseList(ListNode head) {        if(head==null) return null;        ListNode pre = null;        while(head!=null) {            //第一次完成的是第一个节点指向null操作            ListNode tmp = head.next;            head.next = pre;            pre = head;            head = tmp;        }        //退出循环时 head==null pre为原链表最后一个节点        return pre;    }}