算法通关村第二关——反转链表青铜笔记

LeetCode 206.反转链表

建立虚拟结点辅助翻转

public ListNode reverseList(ListNode head) {ListNode ans = new ListNode(-1);ListNode cur = head;while(cur!=null){ListNode curNext = cur.next;cur.next = ans.next;ans.next = cur;cur = curNext;}return ans.next;
}

不带虚拟头结点翻转

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