Pascal's Triangle II

Given an index k, return the kth row of the Pascal’s triangle.

For example, given k = 3,
Return [1,3,3,1].

Note:
Could you optimize your algorithm to use only O(k) extra space?

class Solution:
    # @return a list of integers
    def getRow(self, rowIndex):
            result = []
            for i in range(rowIndex+1):                                                              result.append(self.func(rowIndex) / (self.func(i) * self.func(rowIndex-i)))
            return result
    def func(self, k):
        sum = 1
        for i in range(1, k+1):
            sum = sum * i
        return sum