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?

vector
     
       getRow(int rowIndex)    {        vector
      
       result;        vector
       
        temp;        if (rowIndex < 0)return result;        temp.push_back(1);        if (rowIndex == 0)return temp;                for (int i = 0; i <= rowIndex;i++)        {            result.clear();            result.push_back(1);            for (int j = 1; j < i; j++)            {                result.push_back(temp[j - 1] + temp[j]);            }            result.push_back(1);            temp = result;        }        return result;    }