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

Given an array of strings words, return the words that can be typed using letters of the alphabet on only one row of American keyboard like the image below.
In the American keyboard:

the first row consists of the characters "qwertyuiop",
the second row consists of the characters "asdfghjkl", and
the third row consists of the characters "zxcvbnm".


 
Please complete the following python code precisely:
```python
class Solution:
    def findWords(self, words: List[str]) -> List[str]:
```