45 lines
758 B
Python
45 lines
758 B
Python
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class LinkedListNode:
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def __init__(self, val):
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self.val = val
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self.next = None
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def hasCycle(head):
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if not head:
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return False
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slow = head
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fast = head.next
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while True:
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# if either pointer is null, reached end of list and return False
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if slow is None or fast is None or fast.next is None:
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return False
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# cycle detected, exit and return True
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if slow is fast:
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return True
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# advance pointers
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slow=slow.next
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fast=fast.next.next
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return False
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head = LinkedListNode(1)
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head.next = LinkedListNode(2)
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head.next = head
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# head.next.next = LinkedListNode(3)
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# # head.next.next.next = head.next
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print( hasCycle(head) )
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