1、题目
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.
2、结题思路
1、先得到有效的k,
2、反转所有数组
3、反转下标从0到k的数组
4、 反转下标从k到length - 1的数组
3、代码实现
class Solution { public void rotate(int[] nums, int k) { if (nums == null || nums.length == 0 || k <= 0) return; int length = nums.length; int lastK = 0; if (k < length) lastK = k; else lastK = k % length; if (lastK == 0) return; change(nums, length); change(nums, lastK); int i = lastK, j = length - 1; while (i < j) { int temp = nums[i]; nums[i] = nums[j]; nums[j] = temp; i++; j--; } } public void change(int[] nums, int length) { for (int i = 0; i < length / 2; ++i) { int temp = nums[i]; nums[i] = nums[length - i - 1]; nums[length - i - 1] = temp; } } }
