Please solve the programming task below using a self-contained code snippet in a markdown code block.

You are given an integer length and an array updates where updates[i] = [startIdxi, endIdxi, inci].
You have an array arr of length length with all zeros, and you have some operation to apply on arr. In the ith operation, you should increment all the elements arr[startIdxi], arr[startIdxi + 1], ..., arr[endIdxi] by inci.
Return arr after applying all the updates.
 
Please complete the following python code precisely:
```python
class Solution:
    def getModifiedArray(self, length: int, updates: List[List[int]]) -> List[int]:
```