My solution was accepted but I'm having a tough time figuring out what the time complexity would be for this solution. The number of operations by list is 1 + 2 + 3 + 4 + .... + n would number of operations reduce to n^2 how does the math work and translate into Big-O notation?

I'm thinking this is similar to the gauss formula n(n-1)/2 so O(n^2) but I could be wrong any help is much appreciated

I'm not submitting this as an answer it is a question so i have not gave a detailed explanation of my code. I can If needed though

```
public class Solution {
public List<List<Integer>> generate(int numRows) {
if(numRows < 1) return new ArrayList<List<Integer>>();;
List<List<Integer>> pyramidVal = new ArrayList<List<Integer>>();
for(int i = 0; i < numRows; i++){
List<Integer> tempList = new ArrayList<Integer>();
tempList.add(1);
for(int j = 1; j < i; j++){
tempList.add(pyramidVal.get(i - 1).get(j) + pyramidVal.get(i - 1).get(j -1));
}
if(i > 0) tempList.add(1);
pyramidVal.add(tempList);
}
return pyramidVal;
}
}
```