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.
这道题要求最好用O(1)做出来，我一开始是新建了一个数组，这个reverse三次的方法也不知道怎么找出来的，挺神奇的。
public class Solution { public void rotate(int[] nums, int k) { if (nums == null || nums.length == k || nums.length <= 1) { return; } k = k % nums.length; reverse(nums, 0, nums.length - k - 1); reverse(nums, nums.length - k, nums.length - 1); reverse(nums, 0, nums.length - 1); } public void reverse(int[] nums, int left, int right) { while (left < right) { int tmp = nums[right]; nums[right] = nums[left]; nums[left] = tmp; left++; right--; } } }
原文：http://www.cnblogs.com/aprilyang/p/6339780.html