Keyboard Row

Given a List of words, return the words that can be typed using letters of alphabet on only one row's of American keyboard like the image below.

Example 1:

Input:
 ["Hello", "Alaska", "Dad", "Peace"]

Output:
 ["Alaska", "Dad"]

Note:

1. You may use one character in the keyboard more than once.

2. You may assume the input string will only contain letters of alphabet.

解题思路：

集合运算

判断输入单词的字母集合是否为键盘某一行字母集合的子集

usesetto check the word.First make every line a set of letter.Then I check every word if this word set is the subset if any line set.

class Solution(object):
    def findWords(self, words):
        """
        :type words: List[str]
        :rtype: List[str]
        """
        line1, line2, line3 = set('qwertyuiop'), set('asdfghjkl'), set('zxcvbnm')
        result = []
        for word in words:
            w = set(word.lower())
            if w.issubset(line1) or w.issubset(line2) or w.issubset(line3):
                result.append(word)
        return result

set 的issubset()

s.issubset(t) 与 s <= t 相等：test whether every element in s is in t。