You will need to write a function to solve sorting problem.
ptr is a pointer, len is the length of ptr and is a complete square number, after we allocate it space according by the input.
After sorting ptr in non-descending order, you need to put it in a 2D array in row-major order, then return it in int** type.
you don't need to worry it
A 2D matrix
Remember to change line each row.