leetcode: 61. Rotate List

最新推荐文章于 2025-09-11 19:19:55 发布

原创最新推荐文章于 2025-09-11 19:19:55 发布 · 417 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#leetcode

LeetCode-Python 专栏收录该内容

134 篇文章

订阅专栏

本文介绍了一种链表操作算法——链表右旋转。通过实例详细展示了如何将一个链表向右旋转k个位置的具体实现过程，并给出了完整的Python代码示例。

Problem

# Given a list, rotate the list to the right by k places, where k is non-negative.
#
# Example:
# Given 1->2->3->4->5->NULL and k = 2,
# return 4->5->1->2->3->NULL.

AC

class ListNode:
    def __init__(self, x):
        self.val = x
        self.next = None

class Solution():
    def rotateRight(self, head, k):
        if not head:
            return None
        cur, n = head, 1
        while cur.next:
            cur, n = cur.next, n+1
        cur.next = head
        tail = cur = head
        for _ in range(n - k % n):
            tail, cur = cur, cur.next
        tail.next = None
        return cur


if __name__ == "__main__":
    head, head.next, head.next.next, head.next.next.next, head.next.next.next.next \
        = ListNode(1), ListNode(2), ListNode(3), ListNode(4), ListNode(5)
    print(Solution().rotateRight(head, 2))