题目浅析

  • 想查看原题可以点击题目链接。

  • 简单地说，就是给一个链表，现在要进行 k 次轮换操作，每次轮换会把最后一个结点放到第一个，求最终链表。

思路分享

代码解答（强烈建议自行解答后再看）

  • 参考题解
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# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def rotateRight(self, head: Optional[ListNode], k: int) -> Optional[ListNode]:
        dummy = ListNode(0, head)
        left, right = dummy, dummy

        cur = head
        l = 0
        while cur:
            cur = cur.next
            l += 1
            # if not cur.next:
            #     cur.next = head

        if l == 0:
            return head

        k %= l 
        if k == 0:
            return head

        for _ in range(k):
            if right.next:
                right = right.next
            else:
                right = dummy
        
        while right.next:
            left, right = left.next, right.next

        dummy.next = left.next
        left.next = right.next
        right.next = head

        return dummy.next