Pascal's triangle II

Question: Given a row index, return the triangle at the index layer of the Pascal triangle

Algorithm: generate an index-layer Pascal triangle and return the index-level triangle.

public class Solution {    public List<Integer> getRow(int rowIndex) {        if (rowIndex < 0) {            return null;        }                List<List<Integer>> pascalTriangle = new ArrayList<List<Integer>>();        for (int i=0; i<=rowIndex; ++i) {            if (i == 0) {                List<Integer> currTriangle = new ArrayList<Integer>();                currTriangle.add(1);                pascalTriangle.add(i, currTriangle);            } else {                List<Integer> currTriangle = new ArrayList<Integer>();                List<Integer> lastTriangle = pascalTriangle.get(i-1);                                int lastInteger = 0;                for (int j=0; j<lastTriangle.size(); ++j) {                    currTriangle.add(lastInteger + lastTriangle.get(j));                    lastInteger = lastTriangle.get(j);                }                currTriangle.add(1);                pascalTriangle.add(currTriangle);            }        }// end of for                return pascalTriangle.get(rowIndex);    }}

Pascal's triangle II