Transpose 1 Dimensional Array

Question

So I have a ONE dimensional array with N values, where N is a perfect square. I visualize this one dimensional array as a two dimensional array (although it is not). For example, an array with values int Array = { 0,1,2,3,4,5,6,7,8 }

That is

int *Array = new int [9];                                                                                                                                                                                                    
for ( int i = 0 ; i < 9 ; i ++ )
         Array[i] = i; // For example

This is printed as

0 1 2
3 4 5 
6 7 8

So, I want to interchange the position in the one dimensional array such that I get the transpose of it,...

For example...

0 3 6
1 4 7
2 5 8

This is basically the same one dimensional array , but the values are swapped such that the array is now int Array = {0,3,6,1,4,7,2,5,8}

If I were to scale it to an array of dimension 1024*1024, how will the logic be ?

Answer 1

With n = sqrt(N), you could just try something simple like:

for(int i = 0; i < n; ++i)
    for(int j = i+1; j < n; ++j)
        std::swap(Array[n*i + j], Array[n*j + i]);