大约有 37,000 项符合查询结果（耗时：0.0339秒） [XML]
What are the differences between NP, NP-Complete and NP-Hard?
...al definition. Moreover, "decidable" can also be defined in terms of "computable functions." So, the halting problem is a decision problem ("Does this program halt?" is a yes/no question) but it is undecidable; there is no effective method for determining whether or not an instance of the halting pr...
Build an ASCII chart of the most commonly used words in a given text [closed]
... C:\WINDOWS\system32\A */
/*Recursive common table expression to
generate a table of numbers from 1 to string length
(and associated characters)*/
WITH N AS
(SELECT 1 i,
LEFT(@,1)L
UNION ALL
SELECT i+1,
SUBSTRING(@,i+1,1)
F...
What is the difference between vmalloc and kmalloc?
...ral virtual-to-physical address mappings will have to be added to the page table. And in the worst case, there will be (size of buffer/page size) number of mappings added to the page table.
This also adds pressure on TLB (the cache entries storing recent virtual to physical address mappings) when a...
How to query as GROUP BY in django?
...eturning designation and dcount, what if i want to get other values of the table too?
– A.J.
Mar 5 '14 at 8:02
20
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How can I store my users' passwords safely?
...s anymore! This is only here for historical purposes.
Take a look at: Portable PHP password hashing framework: phpass and make sure you use the CRYPT_BLOWFISH algorithm if at all possible.
Example of code using phpass (v0.2):
<?php
require('PasswordHash.php');
$pwdHasher = new PasswordHash(8...
Android splash screen image sizes to fit all devices
... ). My application is supposed to run good and beautiful on all phones and tablets. What sizes (in pixels) should I create so the splash displays nice on all screens?
...
How much of a git sha is *generally* considered necessary to uniquely identify a change in a given c
... Exactly the question I was trying to solve, thank you! The probability table linked in @Messa's answer is also helpful.
– Kyle Chadha
Jun 16 '17 at 15:36
...
How do you track record relations in NoSQL?
...and indexes in NoSQL KVP or Document databases. Since there are no pivotal tables (to add keys marking a relation between two objects) I am really stumped as to how you would be able to retrieve data in a way that would be useful for normal web pages.
...
What's the best way to get the last element of an array without deleting it?
...ning: count(): Parameter must be an array or an object that implements Countable in Command line code on line 1
W8 = Warning: array_key_last() expects parameter 1 to be array, null given in Command line code on line 1
N1 = Notice: Undefined offset: 0 in Command line code on line 1
N2 = Notice: Only ...
Filter rows which contain a certain string
...
head
#> # A tibble: 6 x 10
#> carat cut color clarity depth table price x y z
#> <dbl> <ord> <ord> <ord> <dbl> <dbl> <int> <dbl> <dbl> <dbl>
#> 1 0.23 Ideal E SI2 61.5 55 326 3.95 3....