[119]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 {
public:
vector<int> getRow(int rowIndex) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
vector<int> result(rowIndex + 1);
for(int i = 0; i <= rowIndex; i++)
{
for(int j = i; j >= 0; j--)
{
if(j == 0 || j == i)
result[j] = 1;
else
result[j] = result[j] + result[j-1];
}
}
return result;
}
};