LeetCode:Pascal's Triangle II

Pascal's Triangle II

Given an index k, return the k^th row of the Pascal's triangle.

For example, given k = 3,
Return [1,3,3,1].

Note:
Could you optimize your algorithm to use only O(k) extra space?

public class Solution {
    public ArrayList<Integer> getRow(int rowIndex) {
        // Start typing your Java solution below
        // DO NOT write main() function
        int []res = new int[rowIndex+1];
        res[0]=1;
        if(rowIndex==0) return getList(res);
        for(int j=1;j<rowIndex+1;j++){
            for(int i=j-1;i>0;i--){
                res[i]=res[i]+res[i-1];
            }
            res[j]=1;
        }
        return getList(res);
    }
    
    public ArrayList<Integer> getList(int[] nums){
        ArrayList<Integer> res = new ArrayList<Integer>();
        for(int i=0;i<nums.length;i++){
            res.add(nums[i]);
        }
        return res;
    }
}