LeetCode刷题（C++）——Rotate List（Medium）

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#LeetCode #C++ #rotate list

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本文介绍了一种算法，用于将单链表向右旋转k个位置。通过双指针技巧实现高效旋转，避免了不必要的元素移动。

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Given a list, rotate the list to the right by k places, where k is non-negative.

For example:
Given 1->2->3->4->5->NULL and k = 2,
return 4->5->1->2->3->NULL.

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* rotateRight(ListNode* head, int k) {
        if (head == NULL)
			return NULL;
		int count = 0;
		ListNode* p = head;
		while (p != NULL)
		{
			count++;
			p = p->next;
		}
		k = k%count;
		if (k == 0)
			return head;
		ListNode* fast = head;
		ListNode* slow = head;
		for (int i = 0; i < k;i++)
			fast = fast->next;
		while (fast->next != NULL)
		{
			fast = fast->next;
			slow = slow->next;
		}
		if (slow->next == NULL)
			return head;
		else
		{
			p = slow->next;
			fast->next = head;
			slow->next = NULL;
			return p;
		}
    }
};