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

Given an array of strings patterns and a string word, return the number of strings in patterns that exist as a substring in word.
A substring is a contiguous sequence of characters within a string.
 
Please complete the following python code precisely:
```python
class Solution:
    def numOfStrings(self, patterns: List[str], word: str) -> int:
```