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题目：Write a program to check whether a given number is an ugly number.Ugly numbers are positive numbers whose prime factors only include2, 3, 5. For ex... 阅读全文
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题目：Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.For example,"A man, a plan, a canal: P... 阅读全文
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题目：Description:Count the number of prime numbers less than a non-negative number,n.提示：求素数个数的比较快速的方法是“埃拉托斯特尼筛法”，其原理很简单，具体的解释可以点击该链接。代码：一个简单的“埃拉托斯特尼筛法”实... 阅读全文
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题目：Given an array of strings, group anagrams together.For example, given:["eat", "tea", "tan", "ate", "nat", "bat"],Return:[ ["ate", "eat","tea"], [... 阅读全文
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题目：Given two stringssandt, determine if they are isomorphic.Two strings are isomorphic if the characters inscan be replaced to gett.All occurrences of... 阅读全文