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Best algorithm for detecting cycles in a directed graph [closed]
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Tarjan's strongly connected components algorithm has O(|E| + |V|) time complexity.
For other algorithms, see Strongly connected components on Wikipedia.
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Avoiding instanceof in Java
...l. Sometimes it isn't even logically the right place to put the code. He recommends the 'instanceof' approach as being the lesser of several evils.
As with all cases where you are forced to write smelly code, keep it buttoned up in one method (or at most one class) so that the smell doesn't leak ou...
Is there any difference between a GUID and a UUID?
...er case characters and are case insensitive on input". This can lead to incompatibilities between code libraries (such as this).
(Original answer follows)
Treat them as a 16 byte (128 bits) value that is used as a unique value. In Microsoft-speak they are called GUIDs, but call them UUIDs when no...
What is the best method of handling currency/money?
...lly convert to and from BigDecimals everywhere, which will probably just become a pain.
As pointed out by mcl, to print the price, use:
number_to_currency(price, :unit => "€")
#=> €1,234.01
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In MySQL, can I copy one row to insert into the same table?
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How do I get a value of datetime.today() in Python that is “timezone aware”?
...alue of datetime.today() to calculate how long ago something was. But it complains:
19 Answers
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Why does “pip install” inside Python raise a SyntaxError?
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pip is run from the command line, not the Python interpreter. It is a program that installs modules, so you can use them from Python. Once you have installed the module, then you can open the Python shell and do import selenium.
The Python shel...
What is N-Tier architecture?
...t does not need to be in physically different machines. Although I don't recommend it, you can host logical tier and database on the same box.
Edit: One implication is that presentation tier and the logic tier (sometimes called Business Logic Layer) needs to cross machine boundaries "across the w...
Difference between a user and a schema in Oracle?
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How to check iOS version?
...) {}
In Objective-C, you need to check the system version and perform a comparison.
[[NSProcessInfo processInfo] operatingSystemVersion] in iOS 8 and above.
As of Xcode 9:
if (@available(iOS 9, *)) {}
The full answer …
In Objective-C, and Swift in rare cases, it's better to avoid relying...