Reverse a singly linked list.
Example:
Input: 1->2->3->4->5->NULL Output: 5->4->3->2->1->NULL
Follow up:A linked list can be reversed either iteratively or recursively. Could you implement both?
public ListNode reverseList(ListNode head) {//链表 迭代 my ListNode nhead = null; ListNode curr = head; while(null!=curr){ head=head.next; curr.next=nhead; nhead=curr; curr=head; } return nhead; }
递归
public ListNode reverseList(ListNode head) { if (head == null || head.next == null) return head; ListNode p = reverseList(head.next); head.next.next = head; head.next = null; return p; }
进阶题
两两交换链表中的结点 LeetCode24 https://www.cnblogs.com/zhacai/p/10559271.html
每 k 个节点一组翻转链表 LeetCode25 https://www.cnblogs.com/zhacai/p/10563446.html