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Valid Parentheses Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. Example The b 阅读全文
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Implement pow(x, n). Notice You don't need to care about the precision of your answer, it's acceptable if the expected answer and your answer 's diffe 阅读全文
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Given a boolean 2D matrix, find the number of islands. Notice 0 is represented as the sea, 1 is represented as the island. If two 1 is adjacent, we co 阅读全文
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Given a string containing only digits, restore it by returning all possible valid IP address combinations. Given a string containing only digits, rest 阅读全文
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Design a data structure that supports the following two operations: addWord(word) andsearch(word) search(word) can search a literal word or a regular 阅读全文
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Design a simplified version of Twitter where users can post tweets, follow/unfollow another user and is able to see the 10 most recent tweets in the u 阅读全文