The idea is simple, a vector multiply a matrix is to sum the vector components with weights. Here is a link

```
class Solution(object):
def multiply(self, A, B):
"""
:type A: List[List[int]]
:type B: List[List[int]]
:rtype: List[List[int]]
"""
ans = []
for arr in A:
line = [0] * len(B[0])
for i in xrange(len(arr)):
if arr[i] != 0:
line = map(sum, zip(line, map(lambda y: arr[i]*y, B[i])))
ans.append(line)
return ans
```