LeetCode----- 61. Rotate List

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.

给定一个单链表，将单链表旋转到右边的k个位置，k为非负数。

解题思路：先判断链表结点个数，然后将单链表构成循环单链表，然后遍历旋转的次数，寻找到头结点。

public class RotateList {
	public static  ListNode rotateRight(ListNode head, int k) {
		if(head == null || head.next == null) {
			return head;
		}
		int length = 0;
		ListNode result = new ListNode(0);
		result.next = head;
		ListNode node = result;
		while(node.next!=null) {
			length++;
			node = node.next;
		}
		node.next = head;//构成循环链表
		for(int i=0;i<length-k%length;i++) {
			node = node.next;
		}
		result.next = node.next;
		node.next = null;
		return result.next;
    }

	public static void main(String[] args) {
		ListNode l10 = new ListNode(1);
		ListNode l11 = new ListNode(2);
		ListNode l12 = new ListNode(3);
		ListNode l13 = new ListNode(4);
		ListNode l14 = new ListNode(5);
		ListNode l15 = new ListNode(6);
		l10.next = l11;
		l11.next = l12;
		l12.next = l13;
		l13.next = l14;
		l14.next = l15;
		l15.next = null;
				
		ListNode node =rotateRight(l10,7);
		while(node != null) {
			if(node.next == null) {
				System.out.println(node.val);
			}else{
				System.out.print(node.val +"->");
			}
			node = node.next;
		}
	}		
}