Maximum Product of Word Length

Given a string array words, find the maximum value of length(word[i]) * length(word[j]) where the two words do not share common letters. You may assume that each word will contain only lower case letters. If no such two words exist, return 0.

Example 1: Given ["abcw", "baz", "foo", "bar", "xtfn", "abcdef"] Return 16 The two words can be "abcw", "xtfn".

Example 2: Given ["a", "ab", "abc", "d", "cd", "bcd", "abcd"] Return 4 The two words can be "ab", "cd".

Example 3: Given ["a", "aa", "aaa", "aaaa"] Return 0 No such pair of words.

Solution

class Solution(object):
    def maxProduct(self, words):
        """
        :type words: List[str]
        :rtype: int
        """
        d = {}
        for w in words:
            mask = 0
            for c in set(w):
                mask |= (1 << (ord(c) - 97))
            d[mask] = max(d.get(mask, 0), len(w))
        return max([d[x] * d[y] for x in d for y in d if not x & y] or [0])