[LeetCode] Pascal's Triangle

Thought:
Basically the same with the previous problem.

Code:
public class Solution {
    public ArrayList<ArrayList<Integer>> generate(int numRows) {
        ArrayList<ArrayList<Integer>> result = new ArrayList<ArrayList<Integer>>();
        for (int i = 0; i < numRows; i++){
            result.add( getRow(i) );
        }
        return result;   
    }
    public ArrayList<Integer> getRow(int rowIndex) {
        if ( rowIndex < 0 ){
            return null;
        }else{
            if( rowIndex == 0 ){
                ArrayList<Integer> result = new ArrayList<Integer>();
                result.add(1);
                return result;
            }else{
                ArrayList<Integer> result = getRow(rowIndex-1);
                result.add(1);
                for(int i = rowIndex-1; i>0; i--){
                    result.set(i, result.get(i) + result.get(i-1));
                }
                result.set(0,1);
                return result;
            }
        }           
    }
}