leetcode JAVA Rotate List 难度系数3 3.20

yundomo

于 2014-02-01 11:20:47 发布

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本文介绍了一种链表右旋转算法的实现方法，通过将链表形成环状结构再进行断点操作，实现了指定位置的旋转。适用于链表操作及数据结构学习。

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Question:

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.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    public ListNode rotateRight(ListNode head, int n) {
		if (head == null)
			return null;
		ListNode myhead = head;
		ListNode first = head;
		ListNode last = head;
		while (first.next != null) {
			first = first.next;
		}
		last = first;
		first.next = head;
		first = head;
		for (int i = 0; i < n; i++) {
			first = first.next;
		}
		while (first != last) {
			first = first.next;
			myhead = myhead.next;
		}
		ListNode resulthead = myhead.next;
		myhead.next = null;
		return resulthead;
	}
}