Pascal's Triangle II

public class Solution {
    public ArrayList<Integer> getRow(int rowIndex) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        ArrayList<Integer> previous = new ArrayList<Integer>();
        ArrayList<Integer> result = new ArrayList<Integer>();
        previous.add(1);
        if(rowIndex == 0)
            return previous;
        previous.add(1);
        if(rowIndex == 1)
            return previous;
        for(int i = 1; i < rowIndex; i++)
        {
            result.clear();
            result.add(1);
            for(int j = 0; j < previous.size() - 1; j++)
            {
                result.add(previous.get(j) + previous.get(j+1));
            }
            result.add(1);
            previous.clear();
            previous.addAll(result);
            
        }
        return result;
    }
}

 

public class Solution {
    public ArrayList<Integer> getRow(int rowIndex) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        ArrayList<Integer> result = new ArrayList<Integer>();
        if(rowIndex == 0){
            result.add(1);
            return result;
        } else if(rowIndex == 1){
            result.add(1);
            result.add(1);
            return result;
        }
        int[] num = new int[rowIndex + 1];
        num[0] = 1;
        num[1] = 1;
        
        for(int j = 2; j <= rowIndex; j++){
            for(int i = j; i >= 0; i--){
                if(i == 0 || i == j){
                    num[i] = 1;
                } else {
                    num[i] = num[i] + num[i - 1];
                }
            }
        }
        for(int i = 0; i <= rowIndex; i++){
            result.add(num[i]);
        }
        return result;
    }
}