Reverse a singly linked list.
Hint:
A linked list can be reversed either iteratively or recursively. Could you implement both?
题意：逆序一个链表
java代码：
/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
*/
class Solution {
public ListNode reverseList(ListNode head) {
ListNode prev = null;
ListNode cur = head;
while(cur!=null){
ListNode next = cur.next;
cur.next = prev;
prev = cur;
cur = next;
}
return prev;
}
}
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