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Finding three elements in an array whose sum is closest to a given number

...We've found the answer. The sum was too small. Move j closer to the end to select the next biggest number. The sum was too big. Move k closer to the beginning to select the next smallest number. For each i, the pointers of j and k will gradually get closer to each other. Eventually they will pass ...
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Difference between string and text in rails?

... load varchar in one go, but store text (and blob) outside of the table. A SELECT name, amount FROM products could, be a lot slower when using text for name than when you use varchar. And since Rails, by default loads records with SELECT * FROM... your text-columns will be loaded. This will probably...
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TLSF源码及算法介绍 - 开源 & Github - 清泛网 - 专注C/C++及内核技术

...(0xFFFFFFFF - PTR_MASK) #define GET_NEXT_BLOCK(_addr, _r) ((bhdr_t *) ((char *) (_addr) + (_r))) #define MEM_ALIGN ((BLOCK_ALIGN) - 1) #define ROUNDUP_SIZE(_r) (((_r) + MEM_ALIGN) & ~MEM_ALIGN) #define ROUNDDOWN_SIZE(_r) ((_r) & ~MEM_ALIGN) #define ROUNDUP(_x, _v) ...
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How can I hash a password in Java?

...te[16]; random.nextBytes(salt); KeySpec spec = new PBEKeySpec("password".toCharArray(), salt, 65536, 128); SecretKeyFactory f = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1"); byte[] hash = f.generateSecret(spec).getEncoded(); Base64.Encoder enc = Base64.getEncoder(); System.out.printf("salt: %s...
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Why is “int i = 2147483647 + 1;” OK, but “byte b = 127 + 1;” is not compilable?

... if the expression is a constant expression (§15.28) of type byte, short, char or int : A narrowing primitive conversion may be used if the type of the variable is byte, short, or char, and the value of the constant expression is representable in the type of the variable. Without this clause, ...
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In Java, how do I convert a byte array to a string of hex digits while keeping leading zeros? [dupli

...ffffff" because of sign extension. So one might need to take the last two characters of the returned string. – Marvo Jul 27 '12 at 20:55 ...
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Reverse a string in Java

... This won't work for Unicode characters outside of BMP, as long as for combining characters. – nau Aug 17 '18 at 11:36 2 ...
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Passing base64 encoded strings in URL

...ed to url-encode it, since base64 strings can contain the "+", "=" and "/" characters which could alter the meaning of your data - look like a sub-folder. Valid base64 characters are below. ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/= ...
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What does {0} mean when initializing an object?

... initialized shall be default-initialized. Example: struct S { int a; char* b; int c; }; S ss = { 1, "asdf" }; initializes ss.a with 1, ss.b with "asdf", and ss.c with the value of an expression of the form int(), that is, 0. You can find the complete spec on this topic here ...
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How to replace all occurrences of a character in string?

What is the effective way to replace all occurrences of a character with another character in std::string ? 15 Answers ...