189. Rotate Array

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

Credits:
Special thanks to @Freezen for adding this problem and creating all test cases.

思路: 三次反转，1：反转前部分，2：反转后部分，3：整个反转。

public class Solution {      void reverse(int[] nums, int start, int end) {          while(start < end) {              int temp = nums[start];              nums[start] = nums[end];              nums[end] = temp;              ++start;              --end;          }      }      public void rotate(int[] nums, int k) {          k = k % nums.length;          reverse(nums, 0, nums.length - 1 );          reverse(nums, 0, k - 1 );          reverse(nums, k, nums.length - 1 );      }  }