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.

Solution:

public class Solution {
    public int maxProduct(String[] words) {
        int[] bitmap = new int[words.length];
        for(int i=0; i<words.length; i++){
            for(char c : words[i].toCharArray()){
                bitmap[i] |= 1<<(c-'a');
            }
        }
        int ans = 0;
        for(int i=0; i<words.length; i++){
            for(int j=i+1; j<words.length; j++){
                if((bitmap[i]&bitmap[j])==0){
                    ans = Math.max(ans, words[i].length()*words[j].length());
                }
            }
        }
        return ans;
    }
}
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