[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].

Note:
Could you optimize your algorithm to use only O(k) extra space?

 

class Solution {

public:

    vector<int> getRow(int rowIndex) {

    // IMPORTANT: Please reset any member data you declared, as

    // the same Solution instance will be reused for each test case.

    vector<int> ans;

    ans.push_back(1);

    for(int i = 1;i <= rowIndex;i++)

    {

        for(int j = i; j > 0;j--)

        {

            if(j == i) ans.push_back(1);

            else

                ans[j] = ans[j - 1] + ans[j];

        }

    }

    return ans;

    }

};