Reverse Linked List
Given the head of a singly linked list, reverse the list, and return the reversed list.
Follow up: A linked list can be reversed either iteratively or recursively. Could you implement both?
Example 1
[1] -> [2] -> [3] -> [4] -> [5] -> null --- [5] -> [4] -> [3] -> [2] -> [1] -> null
Input
head = [1,2,3,4,5]Output
[5,4,3,2,1]Reversing the list changes the order from
[1,2,3,4,5] to [5,4,3,2,1].Example 2
[1] -> [2] -> null --- [2] -> [1] -> null
Input
head = [1,2]Output
[2,1]Reversing the list changes the order from
[1,2] to [2,1].Constraints
- The number of nodes in the list is the range
[0, 5000]. -5000 <= Node.val <= 5000