Maximum Product of Word Lengths

Source

• leetcode: Maximum Product of Word Lengths

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.

Java

public class Solution {
    public int maxProduct(String[] words) {
        int[] mask = new int[words.length];
        for(int i=0; i<words.length; i++){
            for(int j=0; j<words[i].length(); j++){
                mask[i] |= 1<<(words[i].charAt(j)-'a');
            }
        }

        int max=0;
        for(int i=0; i<words.length; i++){
            for(int j=i+1; j<words.length; j++){
                if((mask[i]&mask[j])==0){
                    max = Math.max(max, words[i].length()*words[j].length());
                }
            }
        }
        return max;
    }
}