LeetCode——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.

原题链接：https://oj.leetcode.com/problems/rotate-list/

得到链表长度。链表指向尾节点，将链表首尾相连，向右k%len。得到结果链表的尾节点。

public class RotateList {
	public static void main(String[] args) {
		ListNode head = new ListNode(1);
		ListNode head1 = new ListNode(2);
		ListNode head2 = new ListNode(3);
		ListNode head3 = new ListNode(4);
		ListNode head4 = new ListNode(5);
		head.next = head1;
		head1.next = head2;
		head2.next = head3;
		head3.next = head4;
//		while(head != null){
//			System.out.println(head.val);
//			head = head.next;
//		}
		ListNode ln = new RotateList().rotateRight(head, 2);
		while(ln != null){
			System.out.println(ln.val);
			ln = ln.next;
		}
	}
	public ListNode rotateRight(ListNode head, int n) {
		if(head == null)
			return head;
		int len = 1;
		ListNode tmp = head;
		while(tmp.next != null){
			tmp = tmp.next;
			len ++;
		}
		tmp.next = head;
		n %= len;
		int step = len - n;
		while(step > 0){
			tmp = tmp.next;
			step --;
		}
		head = tmp.next;
		tmp.next = null;
		return head;
	}

}
// Definition for singly-linked list.
 class ListNode {
	int val;
	ListNode next;

	ListNode(int x) {
		val = x;
		next = null;
	}
}