pascals-triangle Java code

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]

]

import java.util.*;
public class Solution {
public ArrayList<ArrayList<Integer>> generate(int numRows) {
ArrayList<ArrayList<Integer>> list = new ArrayList<>();
for (int i = 0; i < numRows; i ++) {
ArrayList<Integer> temp = new ArrayList<>();
for (int j = 0; j <= i; j ++) {
if(j == 0 || j == i) temp.add(1);
else temp.add(list.get(i - 1).get(j - 1) + list.get(i - 1).get(j));
}
list.add(temp);
}
return list;
}
}