There are 3 arrays for values column indices and the row pointers all are given as references in the func call
In CSR format we have the number of elements in a certain row so we can just go through each row in the CSR and multiply with the corrosponding col in x the challenge says only convert A
Make the CSR arrays first its a simple loop just go through the dense matrix if the value is not 0 then add record to csr
Access stuff in sequential order to avoid any cahce issues