leetcode206 反转链表

迭代迭代迭代

晕晕晕

java： 

class Solution {
    public ListNode reverseList(ListNode head) {
        ListNode pre=null;
        ListNode cur=head;
        
        while(cur!=null){
            ListNode tmp=cur.next;
            cur.next=pre;
            pre=cur;
            cur=tmp;
        }
        return pre;

    }
}

python:

class Solution:
    def reverseList(self, head: ListNode) -> ListNode:
        cur,pre=head,None
        while cur:
            tmp=cur.next
            cur.next=pre
            pre=cur
            cur=tmp
        return pre