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?

返回第 k 层 Pascal's Triangle，从0开始数。代码如下：

public class Solution {    public List<Integer> getRow(int rowIndex) {        List<Integer> row = new ArrayList<Integer>();        for (int i = 0; i < rowIndex + 1; i ++) {            row.add(0, 1);            for (int j = 1; j < row.size() - 1; j ++) {                row.set(j, row.get(j) + row.get(j + 1));            }        }        return row;    }}