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1、web.xml千万要放在WEB-INF目录下！！！！！而不是lib里面！ 2、当出现空指针时，找到相应的点，利用System.out.println（）;可以定位到程序走哪一步 3、servlet初始化问题 4、乱码问题：在web.xml中加入jsp的配置内容； 5、各种拼写错误，要杜绝 6、看 阅读全文
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Write a function that takes a string as input and reverse only the vowels of a string. Example 1: Given s = "hello", return "holle". Example 2: Given 阅读全文
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Write a function that takes a string as input and returns the string reversed. Example: Given s = "hello", return "olleh". Subscribe to see which comp 阅读全文
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Given two numbers represented as strings, return multiplication of the numbers as a string. Note: The numbers can be arbitrarily large and are non-neg 阅读全文
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Implement a basic calculator to evaluate a simple expression string. The expression string contains only non-negative integers, +, -, *, / operators a 阅读全文