Equation to solve this in O(k)

#1

The (k+1)th row of the pascal’s triangle is:
kC0, kC1, … kCk
Now, it’s easy to derive: C(n,r) = C(n,r-1) * (n-r+1)/r
Using this recursive relation, an iterative DP will yield the solution easily.

vector<int> Solution::getRow(int n) 
{
    vector<int> ans(n+1);
    ans[0]=1;
    for(int r=1; r<=n; r++)
    {
        ans[r]= (ans[r-1]*(n-(r-1)))/r;
    }
    return ans;
}