leetcode (java) 189. Rotate Array

Q: Given an integer array nums, rotate the array to the right by k steps, where k is non-negative.

A: I can use three methods to solve this problems.

       a) Reverse the array three times.

                For array [1,2,3,4,5] k = 2

                firstly, I reverse the whole array and get arrary[5,4,3,2,1]

                secondly, I reverse the fisrt k numbers and get arrary [4,5,3,2,1]

                thirdly, I reverse the remaining numbers and get array [4,5,1,2,3].

                Now , the array is the answer

class Solution {
    public void rotate(int[] nums, int k) {
        k = k % nums.length;
        reverse(nums, 0, nums.length);
        reverse(nums, 0, k);
        reverse(nums, k, nums.length);
    }

    public static void reverse(int[] nums, int start, int end){
        int t;
        for(int i=start; i<nums.length && end-1-(i-start) < nums.length && i<start + (end-start)/2;i++){
            t = nums[i];
            nums[i] = nums[end-1-(i-start)];
            nums[end-1-(i-start)] = t;
        }
    }
}

     b) New another array and copy numbers from the original array

     c) bubble swap numbers from back to front k times

         every loop will move the last number to the first

        it is similar to the bubble sorting algorithm