Pascal's Triangle

public class Solution {
    public ArrayList<ArrayList<Integer>> generate(int numRows) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        ArrayList<ArrayList<Integer>> result = new ArrayList<ArrayList<Integer>>();
        if(numRows == 0)
            return result;
        ArrayList<Integer> tmp = new ArrayList<Integer>();
        tmp.add(1);
        result.add(tmp);
        
        for(int i = 1; i < numRows; i++)
        {
            tmp = new ArrayList<Integer>();
            tmp.add(1);
            for(int j = 1; j < i; j++)
                tmp.add(result.get(i - 1).get(j - 1) + result.get(i - 1).get(j));
            tmp.add(1);
            result.add(tmp);
        }
        return result;
    }
}