【LeeCode】206. 反转链表

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public ListNode reverseList(ListNode head) {
        if(head == null ){
            return head;
        }
        ListNode olehead = head;
        ListNode myhead = head;
        ListNode tmp = head;

        while(olehead.next!=null){
            tmp = olehead.next;
            olehead.next = tmp.next;
            tmp.next = myhead;
            myhead = tmp;
        }
        return myhead;       
    }
}

思路清晰，推荐此方法

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public ListNode reverseList(ListNode head) {
        //创建myHead，指向null
        //循环开始：head！=null
        //储存head的下一个next
        //储存myHead的下一个myNext
        //myHead指向head，head指向myNext
        //head = next
        //循环结束。
        //返回myHead.next
        ListNode myHead = new ListNode(-1);
        ListNode next = head;
        ListNode myNext = head;
        while(head!=null){
            next = head.next;
            myNext = myHead.next;
            myHead.next = head;
            head.next = myNext;
            head = next;
        }
        return myHead.next;
    }
}