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) {
        
        vector<int> triangle(rowIndex + 1);
        triangle[0] = 1;

        for (int i = 0; i < rowIndex; ++i)
        {
            for (int j = i + 1; j > 0; --j)
            {
                triangle[j] += triangle[j - 1];
            }
        }

        return triangle;
    }
};