Pascal's Triangle II

题目：

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?
解题思路：
类似于Pascal's Triangle I，只是对其做了稍微的修改。

class Solution(object):

def getRow(self, rowIndex):

"""

:type rowIndex: int

:rtype: List[int]

"""

rowIndex += 1

res = []

for i in range(rowIndex):

v = []

for j in range(i+1):

if j==0 or j ==i:

v.append(1)

else:

v.append(res[j-1]+res[j])

res = v

return res