给你一个字符串数组 words ，找出并返回 length(words[i]) * length(words[j]) 的最大值，并且这两个单词不含有公共字母。如果不存在这样的两个单词，返回 0 。
words
length(words[i]) * length(words[j])
0
示例 1：
输入：words = ["abcw","baz","foo","bar","xtfn","abcdef"] 输出：16 解释：这两个单词为 "abcw", "xtfn"。
["abcw","baz","foo","bar","xtfn","abcdef"]
16 解释
这两个单词为 "abcw", "xtfn"
示例 2：
输入：words = ["a","ab","abc","d","cd","bcd","abcd"] 输出：4 解释：这两个单词为 "ab", "cd"。
["a","ab","abc","d","cd","bcd","abcd"]
4 解释
"ab", "cd"
示例 3：
输入：words = ["a","aa","aaa","aaaa"] 输出：0 解释：不存在这样的两个单词。
["a","aa","aaa","aaaa"]
0 解释
不存在这样的两个单词。
提示：
2 <= words.length <= 1000
1 <= words[i].length <= 1000
words[i]
