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# Definition for singly-linked list.
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# class ListNode:
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#     def __init__(self, val=0, next=None):
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#         self.val = val
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#         self.next = next
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class Solution:
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    def rotateRight(self, head: Optional[ListNode], k: int) -> Optional[ListNode]:
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        if k == 0 or head is None or head.next is None:
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            return head
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        cur = head
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        n = 0
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        while cur is not None:
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            cur = cur.next
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            n += 1
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        k = n - k % n
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        if k == n:
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            return head
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        cur = head
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        prev = None
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        while k > 0 and cur is not None:
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            prev = cur
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            cur = cur.next
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            k -= 1
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        prev.next = None
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        prev = cur
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        while cur.next is not None:
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            cur = cur.next
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        cur.next = head
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        return prev