code: import java.util.ArrayList;
  ...//class definition, etc.
  public static void genPyrN(int rows){
  	if(rows < 0) return;
  	//save the last row here
  	ArrayList<Integer> last = new ArrayList<Integer>();
  	last.add(1);
  	System.out.println(last);
  	for(int i= 1;i <= rows;++i){
  		//work on the next row
  		ArrayList<Integer> thisRow= new ArrayList<Integer>();
  		thisRow.add(last.get(0)); //beginning
  		for(int j= 1;j < i;++j){//loop the number of elements in this row
  			//sum from the last row
  			thisRow.add(last.get(j - 1) + last.get(j));
  		}
  		thisRow.add(last.get(0)); //end
  		last= thisRow;//save this row
  		System.out.println(thisRow);
  	}
  }
  