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STL可迭代容器，例如priority_queue

[英]STL iterable container like priority_queue

原文 2013-06-06 22:02:02 2 4 c++/ stl/ containers/ priority-queue

I'm new to STL containers (and C++ in general) so thought I would reach out to the community for help. 我是STL容器（和C ++）的新手，所以我想向社区寻求帮助。 I basically want to have a priority_queue that supports constant iteration. 我基本上想拥有一个支持常量迭代的priority_queue 。 Now, it seems that std::priority_queue doesn't support iteration, so I'm going to have to use something else, but I'm not sure exactly what. 现在，似乎std::priority_queue不支持迭代，因此我将不得不使用其他东西，但是我不确定到底是什么。

Requirements: 要求：

Maintains order on insertion (like a priority queue) 保持插入顺序（例如优先级队列）
Pop from top of list 从列表顶部弹出
Get const access to each element of the list (don't care about the order in the queue for this stage) 获得对列表中每个元素的const访问权限（此阶段无关队列中的顺序）

One option would be to keep a priority_queue and separately have an unordered_set of references, but I'd rather not have two containers floating around. 一种选择是保留一个priority_queue并分别具有一个unordered_set的引用，但是我宁愿不要有两个浮动的容器。 I could also use a deque and search through for the right insertion position, but I'd rather have the container manage the sorting for me if possible (and constant-time insertion would be nicer than linear-time). 我也可以使用deque并搜索正确的插入位置，但我宁愿让容器为我管理排序（并且恒定时间插入比线性时间更好）。 Any suggestions? 有什么建议么？

4 个解决方案

There are two options that come to mind: 有两种选择：

1) Implement your own iterable priority queue, using std::vector and the heap operation algorithms (see Heap Operations here ). 1）实现你自己的迭代优先级队列，使用std::vector和堆操作算法（参见堆操作 在这里）。

2) derive (privately) from priority_queue . 2）（私下）从priority_queue派生。 This gives you access to the underlying container via data member c . 这使您可以通过数据成员c访问底层容器。 You can then expose iteration, random access, and other methods of interest in your public interface. 然后，您可以在公共接口中公开迭代，随机访问和其他感兴趣的方法。

Using a std::vector might be enough as others already pointed, but if you want already-ready implementation, maybe use Boost.Heap (which is a library with several priority queue containers): http://www.boost.org/doc/libs/1_53_0/doc/html/heap.html 使用std :: vector可能已足够，正如其他人已经指出的那样，但是如果您想已经准备好实现，则可以使用Boost.Heap（这是一个具有多个优先级队列容器的库）： http : //www.boost.org/ doc / libs / 1_53_0 / doc / html / heap.html

Boost is a collection of libraries that basically complete the standard library (which is not really big). Boost是基本完成标准库（不是很大）的库的集合。 A lot of C++ developers have boost ready on their dev computer to use it when needed. 许多C ++开发人员已经准备好在其开发计算机上使用它们，以便在需要时使用它。 Just be careful in your choices of libraries. 选择库时要小心。

You can use (ordered) set as a queue. 您可以将（有序）设置为队列。 set.begin() will be your top element, and you can pop it via erase(set.begin()). set.begin（）将是您的顶部元素，您可以通过delete（set.begin（））将其弹出。

Have you observed heap ( std::make_heap ) ? 您是否观察到了堆（ std :: make_heap ）？ It hasn't order inside of queue, but has priority "pop from top of list" which you need. 它没有在队列中排序，但是具有您需要的优先级“从列表顶部弹出”。