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Are duplicate keys allowed in the definition of binary search trees?
I'm trying to find the definition of a binary search tree and I keep finding different definitions everywhere.
12 Answers
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How to validate an email address in PHP
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The easiest and safest way to check whether an email address is well-formed is to use the filter_var() function:
if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
// invalid emailaddress
}
Additionally you can check whether the do...
Rename a class in Xcode: Refactor… is grayed out (disabled). Why?
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Very sad, almost 2 years later and it still won't refactor the Objective-C objects.
– christophercotton
Apr 10 '11 at 22:42
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How to speed up insertion performance in PostgreSQL
...n the PostgreSQL manual, depesz's excellent-as-usual article on the topic, and this SO question.
(Note that this answer is about bulk-loading data into an existing DB or to create a new one. If you're interested DB restore performance with pg_restore or psql execution of pg_dump output, much of thi...
EC2 instance has no public DNS
...as not the one who set it up. Some of the instances show a public dns name and others have a blank public DNS. I want to be able to connect to the instances that have a blank public DNS. I have not been able to figure out why these show up as blank.
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What is “android:allowBackup”?
...e, either open the lint warnings view, where you can select the lint error and see a longer explanation, or invoke the quick fix (Ctrl-1) on the error line, and one of the suggestions is "Explain this issue", which will also pop up a fuller explanation. If you are not using Eclipse, you can generate...
Difference between Role and GrantedAuthority in Spring Security
There are concepts and implementations in Spring Security, such as the GrantedAuthority interface to get an authority to authorize/control an access.
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Visual Studio 2013 doesn't discover unit tests
...isual studio 2013 that is composed by one web project, one library project and one unit test project. When I open the solution and try to run the unit tests they are not discover by visual studio. To run the tests I try to go to the menu and choose Test -> Run -> Run all tests or by opening the test...
Why is a combiner needed for reduce method that converts type in java 8
I'm having trouble fully understanding the role that the combiner fulfils in Streams reduce method.
4 Answers
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How to map and remove nil values in Ruby
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Ruby 2.7 is introducing filter_map for this exact purpose. It's idiomatic and performant, and I'd expect it to become the norm very soon.
For example:
numbers = [1, 2, 5, 8, 10, 13]
enum.filter_map { |i| i * 2 if i.even? }
# => [4, 16, 20]
In your case, as the block evaluates to falsey, simp...