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> iv;if(rowIndex<0){return iv;}int nCount=rowIndex;int i,j;iv.push_back(1);double nValue=1; //要写成doubledouble nDenominator=1;for(i=1;i<=nCount;++i){nValue*=(rowIndex-i+1);nDenominator*=i;iv.push_back((int)(nValue/nDenominator+0.5));}return iv;            }};