Medium
Given an array of strings words, return the maximum value of length(words[i]) * length(words[j]) where the two words share no common letters. If no such pair exists, return 0.
Input: words = ["abcw","baz","foo","bar","xtfn","abcdef"] Output: 16 Explanation: "abcw" and "xtfn" share no letters: 4 * 4 = 16.
Input: words = ["a","aa","aaa","aaaa"] Output: 0