Kth Row of Pascal's Triangle

Given an index k, return the kth row of the Pascal’s triangle.

Pascal’s triangle : To generate A[C] in row R, sum up A’[C] and A’[C-1] from previous row R - 1.

Example:

Input : k = 3

Return : [1,3,3,1]

NOTE : k is 0 based. k = 0, corresponds to the row [1].

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

public class Solution {
    public int[] getRow(int A) {
        int[] ans = new int[A + 1];
        int nC1 = A;
        int r = 1;
        for (int i = 0; i <= A; i++) {
            if (i == 0 || i == A)
                ans[i] = 1;
            else {
                ans[i] = nC1;
                nC1 = nC1 * (A - r) / (1 + r);
                r++;
            }
        }
        return ans;
    }
}