Leetcode Pascal's Triangle

Pascal's Triangle Oct 28 '12
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]
]

Leetcode Pascal's Triangle.java

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