Given `head`, the head of a linked list, determine if the linked list has a cycle in it.
There is a cycle in a linked list if there is some node in the list that can be reached again by continuously following the `next` pointer. Internally, `pos` is used to denote the index of the node that the tail's `next` pointer is connected to. **Note that** `pos` *is not passed as a parameter*.
Return `true` *if there is a cycle in the linked list*. Otherwise, return `false`.
Example 1
Input: head = [3,2,0,-4], pos = 1
Output: true
Explanation: There is a cycle, where the tail connects to the 1st node (0-indexed).
Example 2
Input: head = [1,2], pos = 0
Output: true
Explanation: There is a cycle, where the tail connects to the 0th node.
Example 3
Input: head = [1], pos = -1
Output: false
Explanation: There is no cycle in the linked list.
Constraints
•The number of nodes in the list is in the range [0, 10⁴].