119. 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 List<Integer> getRow(int rowIndex) {
        List<Integer> list = new ArrayList<Integer>();
        if (rowIndex < 0)
            return list;

        for (int i = 0; i < rowIndex + 1; i++) {
            list.add(0, 1);
            for (int j = 1; j < list.size() - 1; j++) {
                list.set(j, list.get(j) + list.get(j + 1));
            }
        }
        return list;
    }
}