Given a string arraywords, find the maximum value oflength(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:

Input:
["abcw","baz","foo","bar","xtfn","abcdef"]
Output: 
16 

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

Example 2:

Input:
["a","ab","abc","d","cd","bcd","abcd"]
Output: 
4 

Explanation: 
The two words can be 
"ab", "cd"
.

Example 3:

Input:
["a","aa","aaa","aaaa"]
Output: 
0 

Explanation: 
No such pair of words.

tag: bitwise

class Solution {
    public int maxProduct(String[] words) {
        if (words == null || words.length == 0) return 0;
        int n = words.length;
        int[] values = new int[n];

        for (int i = 0; i < n; i++){
            String word = words[i];
            values[i] = 0;
            for (char c : word.toCharArray()){
                values[i] |= 1 << (c - 'a');
            }
        }

        int ans = 0;
        for (int i = 0; i < n; i++){
            for (int j = i + 1; j < n; j++){
                if ( (values[i] & values[j]) == 0 && words[i].length() * words[j].length() > ans) ans = words[i].length() * words[j].length();
            }
        }

        return ans;
    }
}