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题目如下： Convert a non-negative integer to its english words representation. Given input is guaranteed to be less than 231 - 1. Example 1: Example 2: Exa 阅读全文
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题目如下： Given a wordlist, we want to implement a spellchecker that converts a query word into a correct word. For a given query word, the spell checker 阅读全文
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题目如下： A binary tree is univalued if every node in the tree has the same value. Return true if and only if the given tree is univalued. Example 1: Exam 阅读全文
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题目如下： Return all non-negative integers of length N such that the absolute difference between every two consecutive digits is K. Note that every number 阅读全文