int arr[6] = {1, 2, 3, 4, 5, 6}; for (int i = 0; i < 6; i += 2) { arr[i] = arr[i] + arr[i+1]; arr[i+1] = arr[i] - arr[i+1]; arr[i] = arr[i] - arr[i+1]; }
{2,1,4,3,6,5}
{1,2,3,4,5,6}
{3,1,4,2,5,3}
{1,3,2,5,4,6}