题解 | #牛牛的矩阵相加#

matrix_list = [[1,2,3], [4,5,6], [7,8,9]]
multi_num = int(input())
matrix_list2 =[]
#matrix_list2 = [multi_num*num for num in matrix_list[i] for i in range(3)]

#matrix_list2 = [multi_num * num for row in matrix_list for num in row]
#for col in matrix_list:
#for i in range(3):
#    matrix_list2[i].append(multi_num * num for num in col for col in matrix_list)

for row in matrix_list:
    matrix_list2.append([multi_num * num for num in row])

print(matrix_list2)

第二次，磕磕绊绊解决，再试一次