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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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  /*
    let a= [1,2,3,4,5,6,7]
    k = 3.
    
    we have to first reverse the whole array by swapping first element with the last one and so on..
    you will get[7,6,5,4,3,2,1]
    
    reverse the elements from 0 to k-1
    reverse the elements 7,6,5
    you will get [5,6,7,4,3,2,1]
    
    reverse the elements from k to n-1
    reverse the elements 4,3,2,1
    you will get[5,6,7,1,2,3,4]
    */
    public void reverse(int[] nums, int start, int end) {
        while (start < end) {
            int temp = nums[start];
            nums[start] = nums[end];
            nums[end] = temp;
            start++;
            end--;
        }    
    }
    
    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);
    }