原题链接: https://oj.leetcode.com/problems/pascals-triangle-ii/
public List<Integer> getRow(int rowIndex) {
if (rowIndex < 0) return new ArrayList<Integer>();
List<Integer> row = new ArrayList<Integer>(rowIndex + 1);
if (rowIndex == 0) {
row.add(1);
} else {
List<Integer> upRow = getRow(rowIndex - 1);
for (int i = 0; i <= rowIndex; i++) {
if (i == 0 || i == rowIndex) {
row.add(1);
} else {
row.add(upRow.get(i - 1) + upRow.get(i));
}
}
}
return row;
}