Rotate Array

【问题描述】

Rotate an array of n elements to the right by k steps.

For example, with n = 7 and k = 3, the array [1,2,3,4,5,6,7] is rotated to [5,6,7,1,2,3,4].

Note:
Try to come up as many solutions as you can, there are at least 3 different ways to solve this problem.

[show hint]

Related problem: Reverse Words in a String II

【思路1】

三次反转，1：反转前部分，2：反转后部分，3：整个反转。
复杂度相对较高

【code】

[java]  view plain  copy

1. public class Solution {  
2.     public void rotate(int[] nums, int k) {  
3.         int temp = k % nums.length;  
4.         reverse(nums, 0, nums.length - temp - 1);  
5.         reverse(nums, nums.length - temp, nums.length - 1);  
6.         reverse(nums, 0, nums.length - 1);  
7.     }  
8.   
9.     private void reverse(int[] nums, int start, int end) {  
10.         for (int i = start, j = end; i < j; i++, j--) {  
11.             int temp = nums[i];  
12.             nums[i] = nums[j];  
13.             nums[j] = temp;  
14.         }  
15.     }  
16. }