119.pascals-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(object):
    def getRow(self, rowIndex):
        """
        :type rowIndex: int
        :rtype: List[int]
        """
        fact = [1] * (rowIndex + 1)
        ans = [1] * (rowIndex + 1)
        for i in range(1, rowIndex + 1):
            fact[i] = fact[i - 1] * i
        for i in range(1, rowIndex):
            ans[i] = fact[-1] / (fact[i] * fact[rowIndex - i])
        return ans