Rotate Array | Leetcode

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

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

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Solution: First Adjust k by doing k %= n so that we do not rotate redundantly.

Perform a three-reverse operation. It is either you know it or you don't.

http://articles.leetcode.com/2010/04/rotating-array-in-place.html

public class Solution {
    public void rotate(int[] nums, int k) {
        k %= nums.length;
        reverse(nums, 0, nums.length - 1);
        reverse(nums, 0, k - 1);
        reverse(nums, k, nums.length - 1);
    }
    
    private void reverse(int[] nums, int first, int last) {
        while (first < last) {
            int temp = nums[first];
            nums[first] = nums[last];
            nums[last] = temp;
            first++;
            last--;
        }
    }
}