61. 旋转链表(Medium)

Python示例

class Solution:
    def rotateRight(self, head: ListNode, k: int) -> ListNode:
        if not head or not head.next: 
            return head 
        n = 0
        p = head 
        while p:
            if p and not p.next:
                end = p 
            n += 1
            p = p.next 
            
        end.next = head  # 连成环
        k = k % n 

        p = head 
        for _ in range(n - k - 1): # n - k 个
            p = p.next 
        res = p.next 
        p.next = None 
        return res