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Decode the Coding Interview in JavaScript: Real-World Examples

Sparse Matrix Multiplication

Understand how to multiply two sparse matrices by converting them into hashmaps to store only non-zero elements. Explore a method that improves efficiency by iterating through these hashmaps to generate the result matrix. This lesson helps you apply algorithmic thinking and data structure optimization techniques relevant to coding interviews.

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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

Javascript (babel-node)
function multiply(A, B){
    // Write your code here
}
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 ...