Keyboard Row — LeetCode 500 Python Solution

The problem

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. Note that the strings are case-insensitive, both lowercased and uppercased of the same letter are treated as if they are at the same row.

Python solution

class Solution:
    def findWords(self, words: List[str]) -> List[str]:
        s1 = set('qwertyuiop')
        s2 = set('asdfghjkl')
        s3 = set('zxcvbnm')
        ans = []
        for w in words:
            s = set(w.lower())
            if s <= s1 or s <= s2 or s <= s3:
                ans.append(w)
        return ans

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 500. Keyboard Row is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Hash Table.

The hash map guide has the Python template for the pattern and the 709 LeetCode problems that use it.

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