leetcode - 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:
std::vector<int> getRow(int rowIndex) {
std::vector<int> triangle(rowIndex + 1);
triangle[0] = 1;
for(int i = 1; i <= rowIndex; i++)
{
for(int j = i; j >= 0; j--)
{
if(i == j) triangle[j] = triangle[j-1];
else if(j) triangle[j] += triangle[j-1];
}
}
return triangle;
}
};