Maximum Product of Word Lengths — LeetCode 318 Python Solution

The problem

Given a string array words, return the maximum value of length(word[i]) * length(word[j]) where the two words do not share common letters. If no such two words exist, return 0.

Example

Input

words = ["abcw","baz","foo","bar","xtfn","abcdef"]

Output

16

Explanation

The two words can be "abcw", "xtfn".

Python solution

class Solution:
    def maxProduct(self, words: List[str]) -> int:
        mask = [0] * len(words)
        ans = 0
        for i, s in enumerate(words):
            for c in s:
                mask[i] |= 1 << (ord(c) - ord("a"))
            for j, t in enumerate(words[:i]):
                if (mask[i] & mask[j]) == 0:
                    ans = max(ans, len(s) * len(t))
        return ans

Complexity

Pattern: Bit Manipulation

Use XOR, masks and the low-bit trick to replace whole data structures with an integer. LeetCode 318. Maximum Product of Word Lengths is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Bit Manipulation.

The bit manipulation guide has the Python template for the pattern and the 194 LeetCode problems that use it.

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