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;    }};