CODE 14: 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?

	public ArrayList<Integer> getRow(int rowIndex) {
		// Start typing your Java solution below
		// DO NOT write main() function
		if (rowIndex < 0) {
			return new ArrayList<Integer>();
		}
		ArrayList<Integer> row = new ArrayList<Integer>();
		row.add(1);
		for (int i = 1; i <= rowIndex; i++) {
			ArrayList<Integer> tmpRow = new ArrayList<Integer>();
			tmpRow.add(1);
			for (int j = 1; j <= i; j++) {
				if (j == i) {
					tmpRow.add(1);
				} else {
					tmpRow.add(row.get(j) + row.get(j - 1));
				}
			}
			row.clear();
			row.addAll(tmpRow);
		}
		return row;
	}