Link: https://leetcode.cn/problems/reverse-linked-list/
Question
difficulty: easy
adj diff: 3
Given the head of a singly linked list, reverse the list, and return the reversed list.
Example 1:
Input: head = [1,2,3,4,5]
Output: [5,4,3,2,1]
Example 2:
Input: head = [1,2]
Output: [2,1]
Example 3:
Input: head = []
Output: []
Constraints:
The number of nodes in the list is the range [0, 5000].
-5000 <= Node.val <= 5000
Code
public ListNode reverseList(ListNode head) {
ListNode pre = null;
ListNode cur = head;
while (cur != null) {
ListNode next = cur.next;
cur.next = pre;
pre = cur;
cur = next;
}
return pre;
}