23 lines
562 B
Python
23 lines
562 B
Python
# https://leetcode.com/problems/linked-list-cycle
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from typing import Optional
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class ListNode:
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val: int
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next: Optional["ListNode"]
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class Solution:
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def hasCycle(self, head: Optional[ListNode]) -> bool:
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first: Optional[ListNode] = head
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second: Optional[ListNode] = head
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while first is not None and \
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first.next is not None and \
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second is not None:
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first = first.next.next
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second = second.next
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if first == second:
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return True
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return False
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