Reverse Linked List

Given the head of a singly linked list, reverse the list and return the new head.

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Example 1

Input: head = [1, 2, 3, 4, 5]
Output: [5, 4, 3, 2, 1]
Explanation: Each node's next pointer is redirected to the previous node; the old tail (5) becomes the new head.

Example 2

Input: head = [1, 2]
Output: [2, 1]
Explanation: The two-node list is reversed so 2 becomes the new head.

Example 3

Input: head = []
Output: []
Explanation: An empty list reversed is still empty.

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Constraints

• The number of nodes is in the range [0, 5000].
• -5000 <= Node.val <= 5000