LeetCode:Pascal's Triangle

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 class Solution {
    public ArrayList<ArrayList<Integer>> generate(int numRows) {
        // Start typing your Java solution below
        // DO NOT write main() function
        ArrayList<ArrayList<Integer>> res = new ArrayList<ArrayList<Integer>>();
        for(int i=0;i<numRows;i++){
            ArrayList<Integer> temp = new ArrayList<Integer>();
            temp.add(1);
            if(i>0){
                for(int j=0;j<res.get(i-1).size()-1;j++){
                    temp.add(res.get(i-1).get(j)+res.get(i-1).get(j+1));
                }
            temp.add(1);
            }
            
            res.add(temp);
        }
        return res;
    }
}