Sparse Matrix Multiplication
Given two sparse integer matrices A and B. Return the result of AB.
Review the rules of multiple two matrices here
Below is a graphical demonstration of matrix multiplication:
A "sparse" matrix is a matrix where most entries are zero. You may assume that the number of columns in A is equal to that of the number of rows in B.
Input
a: an integer matrix.b: an integer matrix.
Output
An integer matrix represent the product of the above matrices.
Examples
Example 1:
Input:
a = [[1, 0, 3], [0, 1, 2]] b = [[0, 1], [1, 3], [0, 0]]
Output: [[0, 1], [1, 3]]
Explanation: