set

问题 Description : I implemented the following class LabSetInt64 (see below code). The goal here is to manipulate large sets of big integers (up to values of 10M) as fast as possible. My main requirements are focused on : !Crucial : Getting the size/cardinality of a set as fast as possible !Important : Being able to iterate very fast through a set So, starting from the implementation below, it still remain two points I would like to discuss with you. The "popcount()" lazy implementation int

问题 My question is related to this. I wanted to perform a sort() operation over the set with the help of a lambda expression as a predicate. My code is #include <set> #include <string> #include <iostream> #include <algorithm> int main() { using namespace std; string s = "abc"; set<string> results; do { for (int n = 1; n <= s.size(); ++n) { results.insert(s.substr(0, n)); } } while (next_permutation(s.begin(), s.end())); sort (results.begin(),results.end());[](string a, string b)->bool{ size_t

问题 Under certain situations, I need to evict the oldest element in a Java Set . The set is implemented using a LinkedHashSet, which makes this simple: just get rid of the first element returned by the set's iterator: Set<Foo> mySet = new LinkedHashSet<Foo>(); // do stuff... if (mySet.size() >= MAX_SET_SIZE) { Iterator<Foo> iter = mySet.iterator(); iter.next(); iter.remove(); } This is ugly: 3 lines to do something I could do with 1 line if I was using a SortedSet (for other reasons, a SortedSet

问题 I am trying to define and initialize a MySQL variable for a query. I have the following: declare @countTotal int; SET @countTotal = select COUNT(*) from nGrams; I am using MySQL in Netbeans and it tells me I have an error. What/where is my error? How can I fix this? 回答1: MySQL has two different types of variable: local variables (which are not prefixed by @ ) are strongly typed and scoped to the stored program block in which they are declared. Note that, as documented under DECLARE Syntax:

问题 I like to use percents for all position in my apps . I always use same system. I am new at android programming. This is the class : public class SCREEN { DisplayMetrics dm = new DisplayMetrics(); Point size_ = new Point(); int width; int height; // DisplayMetrics metrics = Resources.getSystem().getDisplayMetrics(); SCREEN (Context CONTEXT_) { dm = CONTEXT_.getResources().getDisplayMetrics(); int densityDpi = dm.densityDpi; height = dm.heightPixels; width = dm.widthPixels; } // get full width

问题 How do I use the SET command in windows for floating point arithmatic. /A stands for arithmetic and %VAR% prints the data of VAR not the name. For example when I do: SET /A VAR="2.5+3.1" ECHO %VAR% pause I get the error: 'Missing Operator'. The output (5.6) should be converted to floating point too I'm still busy learning the basic syntax. Regards, Snipe 回答1: The arithmetic operations of SET /A command are performed over 32-bits integer numbers only; however, you may easily simulate fixed

问题 I think this is simply a general c++ question: I'm attempting to compile a local version of ffmpeg on Linux Fedora using the gnu c++ compiler. I have source code in a bunch of folders under: ~/<username>/Downloads/Code/ffmpeg_sources/ which is where I'm attempting to set the config flags to install the build to a target not under this tree but at a root level directory with local shared libraries: /usr/local/ There is this following section near the beginning of the configuration file:

问题 This question already has answers here : How to initialize HashSet values by construction? (23 answers) Closed 5 years ago . In Java, how do I create a final Set that's populated at construction? I want to do something like the following: static final Set<Integer> NECESSARY_PERMISSIONS = new HashSet<Integer>([1,2,3,6]); but I don't know the proper syntax in Java. 回答1: Try this idiom: import java.util.Arrays; new HashSet<Integer>(Arrays.asList(1, 2, 3, 6)) 回答2: You might consider using Guava's

问题 All I desire is to use some concurrent Set (that appears not to exist at all). Java uses java.util.concurrent.ConcurrentHashMap<K, Void> to achieve that behavior. I'd like to do sth similar in Scala so I created instance of Scala HashMap (or Java ConcurrentHashMap) and tried to add some tuples: val myMap = new HashMap[String, Unit]() myMap + (("myStringKey", Unit)) This of course crashed the process of compilation as Unit is abstract and final. How to make this work? Should I use Any / AnyRef

问题 I have seen some some projects in which classes are having get and set methods to manipulate insert data. Let me have an example here : class Student extends dbClass { private $TableID; private $FullName; private $Gender; private $Address; function setTableID($Value) { $this->TableID = $Value; } function getTableID() { return $this->TableID; } function setFullName($Value) { $this->FullName = $Value; } function getFullName() { return $this->FullName; } function setGender($Value) { $this-