题目描述

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

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

分析

和旋转字符串是一样的，先部分旋转，再整体旋转。

代码

    static void reverse(int[] nums, int st, int ed) {

        while (st < ed) {
            int t = nums[st];
            nums[st] = nums[ed];
            nums[ed] = t;
            st++;
            ed--;
        }
    }

    public static void rotate(int[] nums, int k) {

        int length = nums.length;

        k = k % length;

        if (length == 1 || k == 0)
            return;

        reverse(nums, 0, length - k - 1);
        reverse(nums, length - k, length - 1);
        reverse(nums, 0, length - 1);
    }