Leetcode 题目解析之 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

Hint:

Could you do it in-place with O(1) extra space?

Related problem: Reverse Words in a String II

    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 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);
    }