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].

class Solution {public:    vector<int> getRow(int rowIndex)     {        vector<int> v;        vector<vector<int>> vv;        v.push_back(1);        vv.push_back(v);        v.push_back(1);        vv.push_back(v);        for(int i=2; i<=rowIndex; i++)        {            v.clear();            v.push_back(1);            for(int j=1; j<i; j++)                v.push_back(vv[i-1][j-1] + vv[i-1][j]);            v.push_back(1);            vv.push_back(v);        }        return vv[rowIndex];    }};