declaring a priority_queue in c++ with a custom comparator
Feb 2, 2015 · However, the syntax to do so is much simpler than shown there: class Node; bool Compare(Node a, Node b); std::priority_queue<Node, std::vector<Node>, decltype(&Compare)> openSet(Compare); That is, there is no need to explicitly encode the function's type, you can let the compiler do that for you using decltype.
C++ std::priority_queue uses the lambda expression
Dec 9, 2016 · As mentioned, the issue is that the third parameter of the template requires a type, not a value. However, from C++20 non-capturing lambdas are default-constructable. Since every lambda has a unique type, this means that the following will work: std::priority_queue<int, std::vector<int>, decltype([](int lhs, int rhs) {.
c++ - How to iterate over a priority_queue? - Stack Overflow
C++ priority_queue does not offer a .begin() pointer (like vector would do) that you can use to iterate over it. If you want to iterate over the priority queue to search for whether it contains a value then maybe create a wrapper priority queue and use a hash set to keep track of what you have in the queue.
c++ - priority queue clear method - Stack Overflow
May 17, 2010 · Here's a clean and simple method to clear any priority_queue (and queue, and most other containers as well): template <class Q>. void clearQueue(Q & q) {. q = Q(); } Since it's a template, you don't have to remember all the template parameters. Example: std::priority_queue<MyType> simpleQueue;
java - How do I use a PriorityQueue? - Stack Overflow
Mar 25, 2009 · Java 8 solution. We can use lambda expression or method reference introduced in Java 8. In case we have some String values stored in the Priority Queue (having capacity 5) we can provide inline comparator (based on length of String) : Using lambda expression. PriorityQueue<String> pq=. new PriorityQueue<String>(5,(a,b) -> a.length() - b.length());
c++ - How can I create Min stl priority_queue? - Stack Overflow
Mar 13, 2010 · @DhruvMullick It's a little confusing but think of the compare function to return true when you want to put the element at the bottom of the priority queue, and false to put the element at the top of the priority queue. Since default implementation is std::less, that will put the smallest element at the bottom of the priority queue and ...
Time complexity of a Priority Queue in C++ - Stack Overflow
Jun 20, 2017 · This corresponds to the std::priority_queue constructors that accept a container parameter. If you have an empty priority queue to which you want to add n items, one at a time, then the complexity is O (n * log (n)). So if you have all of the items that will go into your queue before you build it, then the first method will be more efficient.
C++ use std::greater () in priority_queue and sort - Stack Overflow
Jul 5, 2019 · class priority_queue; In this statement. sort (numbers.begin(), numbers.end(), std::greater<int>()); there is used the default constructor to create a temporary object of the type greater<int>. std::greater is a template structure. template<class T = void> struct greater; that is its specialization provides a type.
java - Change priorityQueue to max priorityqueue - Stack Overflow
The elements of the priority queue are ordered according to their natural ordering, or by a Comparator provided at queue construction time. The Comparator should override the compare method. int compare(T o1, T o2)
c++ - Efficiency of the STL priority_queue - Stack Overflow
The priority queue adaptor uses the standard library heap algorithms to build and access the queue - it's the complexity of those algorithms you should be looking up in the documentation. The top() operation is obviously O(1) but presumably you want to pop() the heap after calling it which (according to Josuttis ) is O(2*log(N)) and push() is O ...