Keyboard Row

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".

Example 1:

Input: words = ["Hello","Alaska","Dad","Peace"]
Output: ["Alaska","Dad"]

Example 2:

Input: words = ["omk"]
Output: []

Example 3:

Input: words = ["adsdf","sfd"]
Output: ["adsdf","sfd"]

Constraints:

• 1 <= words.length <= 20
• 1 <= words[i].length <= 100
• words[i] consists of English letters (both lowercase and uppercase). 

SOLUTION:

from collections import Counter

class Solution:
    def findWords(self, words: List[str]) -> List[str]:
        rows = [Counter("qwertyuiop"), Counter("asdfghjkl"), Counter("zxcvbnm")]
        op = []
        for word in words:
            isValid = False
            for ctr in rows:
                valid = len([c for c in word if ctr[c.lower()] == 0]) == 0
                if valid:
                    isValid = True
                    break
            if isValid:
                op.append(word)
        return op