Pascal's Triangle

PascalTriangle.java

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