2021.03.23 打卡 LeetCode 206. 反转链表

LeetCode 206. 反转链表

时间复杂度 O(n)

Java

class Solution {
    public ListNode reverseList(ListNode head) {
        ListNode prev = null;
        while (head != null){
            ListNode temp = head.next;
            head.next = prev;
            prev = head;
            head = temp;
        }
        return prev;
    }
}

//runtime:0 ms
//memory:38.3 MB

Python

class Solution:
    def reverseList(self, head):
        cur, prev = head, None
        while cur:
            cur.next, prev, cur = prev, cur, cur.next
        return prev
# runtime:52 ms
# memory:7.7 MB