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Decode the Coding Interview in Ruby: Real-World Examples

Sparse Matrix Multiplication

Explore how to multiply sparse matrices by converting them into hashmaps to store non-zero elements. Understand the algorithmic approach to efficiently compute the product matrix while minimizing time and space complexity.

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Description

We have two sparse matrices, A and B.

“A sparse matrix is one in which most of the elements are zero.”

You need to multiply the two matrices and return the output matrix. You can assume that A’s column number is equal to B’s row number.

Constraints

The following are some constraints:

  • 1 <= A.length, B.length <= 100
  • 1 <= A[i].length, B[i].length <= 100
  • -100 <= A[i][j], B[i][j] <= 100

Let’s review this scenario using the example below:

Coding exercise

Ruby
def multiply(matrix_A, matrix_B)
end
Sparse Matrix Multiplication

Solution

We have two sparse matrices, meaning most of the matrices’ elements are zero. We can represent the input matrices as hashmaps, and only save the non-zero elements and ...