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

Given an integer array nums and an integer k, return the maximum length of a subarray that sums to k. If there is not one, return 0 instead.
 
Please complete the following python code precisely:
```python
class Solution:
    def maxSubArrayLen(self, nums: List[int], k: int) -> int:
```