Given an array of words
words sorted in an alien alphabet order. Recover the order of characters in the alphabet. If the order is contradictory, return an empty string.Example 1
Input: words = ["z","x","z"]
Output: ""
Explanation: Contradiction in the ordering.
Output: ""
Explanation: Contradiction in the ordering.
Example 2
Input: words = ["wrt","wrf","er","ett","rftt"]
Output: "wertf"
Explanation: Order of characters in the alien alphabet.
Output: "wertf"
Explanation: Order of characters in the alien alphabet.