Swap the array elements

problem statement

Given an array arr of n positive integers. The task is to swap every ith element of the array with (i+2)th element.

Example 1:

Input:
n = 3
arr[] = 1 2 3
Output:
3 2 1
Explanation:
Swapping 1 and 3, makes the array 3 2 1. There is only one swap possible in this array.

Example 2:

Input:
n = 5
arr[] = 1 2 3 4 5
Output:
3 4 5 2 1
Explanation:
Swapping 1 and 3, makes the array 3 2 1 4 5.
Now, swapping 2 and 4, makes the array 3 4 1 2 5. 
Again,swapping 1 and 5, makes the array 3 4 5 2 1.

Your Task:
Your task is to complete the function swapElements(), which should swap each ith element with (i+2)th element.

Expected Time Complexity: O(n)
Expected Auxilary Space: O(1)

Constraints:
1 <= n <= 106
0 <= arri <= 109

Approach : straight swapping

Solution :

class Solution
{
    /*
    Time : O(n);
    Space : O(1)
    */
    public void swapElements(int[] arr, int n)
    {
        // Code here
        for(int i=0;i<n-2;i++){
            this.swap(arr,i,i+2);
        }
    }
    public void swap(int[] arr, int i, int j){
        int temp=arr[i];
        arr[i]=arr[j];
        arr[j]=temp;
    }
}