SQL & PL/SQL

I am to write a stored procedure that returns the Levenshtein Distance between 2 strings (similarity ratio). According to sample code designed for Java or VBA, intermediate calculation results are stored in 2-dimensional Arrays, e.g. value_array[1][5] = 7

Has anyone an idea on how
a) to implement the Levenshtein Distance formula in PL/SQL, or
b) how to properly use Arrays in PL/SQL (which seem not to be supported)

Thanks in advance for any kind of help I can get on this.