LeetCode 269. Alien Dictionary - 拓扑排序（Topological Sort）系列题7

最新推荐文章于 2025-04-05 22:04:04 发布

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最新推荐文章于 2025-04-05 22:04:04 发布

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分类专栏：拓扑排序(Topological Sort) Leetcode刷题笔记文章标签： leetcode 算法数据结构 python 拓扑排序

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这道LeetCode难题通过拓扑排序解决外星语字典排序问题。根据给定的有序单词列表，确定字母间的先后顺序并返回排序后的唯一字母字符串。如果存在多种解决方案或无解，则返回空字符串。

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There is a new alien language that uses the English alphabet. However, the order among the letters is unknown to you.

You are given a list of strings words from the alien language's dictionary, where the strings in words are sorted lexicographically by the rules of this new language.

Return a string of the unique letters in the new alien language sorted in lexicographically increasing order by the new language's rules. If there is no solution, return "". If there are multiple solutions, return any of them.

A string s is lexicographically smaller than a string t if at the first letter where they differ, the letter in s comes before the letter in t in the alien language. If the first min(s.length, t.length) letters are the same, then s is smaller