def sparse_matrix_multiplication(matrix_a, matrix_b):
if len(matrix_a[0]) != len(matrix_b):
return [[]]
matrix_c = [[0] * len(matrix_b[0]) for _ in range(len(matrix_a))]
for i in range(len(matrix_c)):
for j in range(len(matrix_c[0])):
for k in range(len(matrix_b)):
if matrix_a[i][k] == 0 or matrix_b[k][j] == 0:
continue
matrix_c[i][j] += matrix_a[i][k] * matrix_b[k][j]
return matrix_c