EasyLinked Lists
Reverse Linked List
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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: []
Examples
Example 1
Input: head = [1,2,3,4,5]
Output: [5,4,3,2,1]
Explanation: The linked list 1 -> 2 -> 3 -> 4 -> 5 becomes 5 -> 4 -> 3 -> 2 -> 1 after reversal.
Example 2
Input: head = [1,2]
Output: [2,1]
Explanation: The linked list 1 -> 2 becomes 2 -> 1 after reversal.
Constraints
- -The number of nodes in the list is the range [0, 5000].
- --5000 <= Node.val <= 5000
Optimal Complexity
Time
O(n)
Space
O(1)
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