وبلاگ الگوریتم های من「141. چرخه لیست پیوندی」

Input: head = [3,2,0,-4], pos = 1
Input: head = [1,2], pos = 0

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

class Solution:
    def hasCycle(self, head: Optional[ListNode]) -> bool:
        if not head:
            return False

        fast = slow = head

        while fast.next != None:
            if fast.next.next == None:
                return False
            else:
                fast = fast.next.next
                slow = slow.next
                if fast == slow:
                    return True

        return False

class Solution:
    def hasCycle(self, head: Optional[ListNode]) -> bool:
        if not head:
            return False

        slow = head
        fast = head.next

        while slow != fast:
            if fast is None or fast.next is None:
                return False
            slow = slow.next
            fast = fast.next.next
        return True