Pascal's Triangle

Given numRows, generate the first numRows of Pascal's triangle.

For example, given numRows = 5,

Return

[     [1],    [1,1],   [1,2,1],  [1,3,3,1], [1,4,6,4,1]]

public List<List<Integer>> generate(int numRows) {ArrayList<List<Integer>> result =new ArrayList<List<Integer>>();List<Integer> lt=new ArrayList<Integer>();if(numRows<=0)return result;lt.add(1);result.add(lt);for(int i=2;i<=numRows;i++){List<Integer> cur=new ArrayList<Integer>();cur.add(1);for(int j=0;j<lt.size()-1;j++)cur.add(lt.get(j)+lt.get(j+1));cur.add(1);result.add(cur);lt=cur;}return result;}