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].

用三个反转，空间复杂度为O(1)

public class Solution {    public void rotate(int[] nums, int k) {        k%=nums.length;        reverse(nums,0,nums.length-1-k);        reverse(nums,nums.length-k,nums.length-1);        reverse(nums,0,nums.length-1);    }    public void reverse(int[] nums,int start,int end){        int length=end-start+1;        for(int i=0;i<length/2;i++){            int temp=nums[end-i];            nums[end-i]=nums[start+i];            nums[start+i]=temp;        }    }}