CODE 72. Rotate List

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版权声明：本文为博主原创文章，转载请注明出处：http://blog.jerkybible.com/2013/10/09/2013-10-09-CODE 72 Rotate List/

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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.

public ListNode rotateRight(ListNode head, int n) {
	// Note: The Solution object is instantiated only once and is reused by
	// each test case.
	if (null == head) {
		return null;
	}
	ListNode round1 = null;
	ListNode p = head;
	int length = 0;
	while (null != p) {
		ListNode node = new ListNode(p.val);
		node.next = round1;
		p = p.next;
		round1 = node;
		length++;
	}
	if (n % length == 0) {
		return head;
	} else {
		n = n % length;
	}
	int num = 0;
	ListNode round2 = null;
	ListNode p1 = round1;
	while (num < n) {
		ListNode node = new ListNode(p1.val);
		node.next = round2;
		p1 = p1.next;
		round2 = node;
		num++;
	}

	ListNode round3 = new ListNode(0);
	ListNode round3Cpy = round3;
	ListNode p2 = round2;
	while (null != p2) {
		ListNode node = new ListNode(p2.val);
		p2 = p2.next;
		round3Cpy.next = node;
		round3Cpy = round3Cpy.next;
	}
	while (null != p1) {
		ListNode node = new ListNode(p1.val);
		node.next = round3Cpy.next;
		round3Cpy.next = node;
		p1 = p1.next;
	}
	return round3.next;
}