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?

下标标错了，改一次通过，总体上是水题，不过也许有空间使用更少的算法。

class Solution {
public:
    vector<int> getRow(int rowIndex) {
        vector <int>vec;
        vec.push_back(1);
        for(int i = 0 ; i < rowIndex ; i++)vec.push_back(1);
        if(rowIndex == 1) return vec;
        
        for(int i = 1; i <=rowIndex ; i++)
        {
            vector<int> ve = vec;
            for(int j = 1; j < i ; j++)vec[j] = ve[j-1]+ve[j];
        }
        return vec;
    }
};