leetcode-top面试题 反转链表

题目
反转一个单链表。
示例:
输入: 1->2->3->4->5->NULL
输出: 5->4->3->2->1->NULL
思路
方法一：迭代

public ListNode reverseList(ListNode head) {
    ListNode prev = null;
    ListNode curr = head;
    while (curr != null) {
        ListNode nextTemp = curr.next;
        curr.next = prev;
        prev = curr;
        curr = nextTemp;
    }
    return prev;
}

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;
}

作者：LeetCode
链接：https://leetcode-cn.com/problems/two-sum/solution/fan-zhuan-lian-biao-by-leetcode/
来源：力扣（LeetCode）
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