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

You are given a 0-indexed m x n integer matrix grid. The width of a column is the maximum length of its integers.

For example, if grid = [[-10], [3], [12]], the width of the only column is 3 since -10 is of length 3.

Return an integer array ans of size n where ans[i] is the width of the ith column.
The length of an integer x with len digits is equal to len if x is non-negative, and len + 1 otherwise.
 
Please complete the following python code precisely:
```python
class Solution:
    def findColumnWidth(self, grid: List[List[int]]) -> List[int]:
```