119. Pascal's Triangle II

Given an index k, return the k^th 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?

C++代码：

class Solution {
public:
    vector<int> getRow(int rowIndex) {
        vector<int> row;
        row.push_back(1);
        for(int i=0;i<=rowIndex;i++)
        {
            vector<int> temp_row;
            row.push_back(0);
            int n=0;
            for(int j=0;j<=i;j++)
            {
                n+=row[j];
                temp_row.push_back(n);
                n=row[j];
            }
            row=temp_row;
        }
        return row;
    }
};