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

You are given an integer array arr. You can choose a set of integers and remove all the occurrences of these integers in the array.
Return the minimum size of the set so that at least half of the integers of the array are removed.
 
Please complete the following python code precisely:
```python
class Solution:
    def minSetSize(self, arr: List[int]) -> int:
```