Alien Dictionary
Explore how to apply topological sort to derive the unique letter order of an alien language from a given list of words. This lesson guides you in understanding lexicographical rules, identifying valid letter sequences, and implementing an algorithm to produce the correct order or determine if none exists, enhancing your problem-solving skills for coding interviews.
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Statement
You are given a list of words written in an alien language, where the words are sorted lexicographically by the rules of this language. Surprisingly, the aliens also use English lowercase letters, but possibly in a different order.
Given a list of words written in the alien language, return a string of unique letters sorted in the lexicographical order of the alien language as derived from the list of words.
If there’s no solution, that is, no valid lexicographical ordering, you can return an empty string "".
If multiple valid orderings exist, you may return any of them.
Note: A string,
a, is considered ...