Linked List Cycle

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    def hasCycle(self, head: ListNode) -> bool:
        """Check if a linked list has cycles

        Time: O(n)
        Space: O(1)
        """

        if not head:
            return False

        slowPointer = head
        fastPointer = head

        while slowPointer.next and fastPointer.next:
            slowPointer = slowPointer.next
            if fastPointer.next.next:
                fastPointer = fastPointer.next.next
            else:
                return False

            if slowPointer and (slowPointer == fastPointer):
                return True

        return False