A matrix is called a Sparse Matrix if majority of its elements are zero.Storing a sparse matrix as list$-$of$-$lists is not very efficient.Alternatively, one can store only the non$-$zero elements, by using a dictionary in Python.keys: indices $($i$,$j$)$ of nonzero elementsvalues: non$-$zero values to be stored.In order to keep the size of the matrix, add a special key size, which contains a tuple $($n$,$m$)$ containing the matrix