Pharo exercice that manipulates sparse matrices
# sparseMatrix [Pharo exercise](https://www.geeksforgeeks.org/sparse-matrix-representation/) that manipulates sparse matrices. A sparse matrix is a matrix with most of its elements equal to 0. For example, this is a sparse matrix : ``` 0 0 3 0 4 0 0 5 7 0 0 0 0 0 0 0 2 6 0 0 ``` The goal of this exercise is to change it to a "compact" matrix and vice versa : ``` Row : 0 0 1 1 3 3 Column : 2 4 2 3 1 2 Value : 3 4 5 7 2 6 ``` It contains 3 methods : `createMatrixWithRow: andColumn:`, `sparseMatrix` and `unsparseMatrix` ## createMatrixWithRow: andColumn: Creates a matrix with given rows and columns, or just an empty array if given 0. This matrix will be by default filled with zeros. ## sparseMatrix Takes a "compact" matrix and return it as a sparse matrix with each value different from 0 at its position and the rest filled with zeros. ## unsparseMatrix Takes a sparse matrix and return it as a 2D array with each value different from 0 and its row and column.