multiply.py

"""
This algorithm takes two compatible two dimensional matrix
and return their product
Space complexity: O(n^2)
Possible edge case: the number of columns of multiplicand not consistent with
the number of rows of multiplier, will raise exception
"""


def multiply(multiplicand: list, multiplier: list) -> list:
    """
    :type A: List[List[int]]
    :type B: List[List[int]]
    :rtype: List[List[int]]
    """
    multiplicand_row, multiplicand_col = len(
        multiplicand), len(multiplicand[0])
    multiplier_row, multiplier_col = len(multiplier), len(multiplier[0])
    if(multiplicand_col != multiplier_row):
        raise Exception(
            "Multiplicand matrix not compatible with Multiplier matrix.")
    # create a result matrix
    result = [[0] * multiplier_col for i in range(multiplicand_row)]
    for i in range(multiplicand_row):
        for j in range(multiplier_col):
            for k in range(len(multiplier)):
                result[i][j] += multiplicand[i][k] * multiplier[k][j]
    return result