[LeetCode] 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?

class Solution {
public:
    vector<int> getRow(int rowIndex) {
        vector<int> temp;;
        temp.push_back(1);
        if(rowIndex==0)
            return temp;
        temp.push_back(1);
        if(rowIndex==1)
            return temp;
        for(int i=2;i<=rowIndex;i++){
          vector<int> res(i+1,1);
          for(int j=1;j<i;j++)
              res[j]=temp[j]+temp[j-1];
          temp = res;
        
        }


        return temp;
    }
};