问题描述
我有一个应用程序（C ++），我认为将很好地服务于STL priority_queue 。 说：
和
我以前曾经假设 / code>是 O（1），并且 push（）将是 O（logn）（我首先选择 priority_queue 的两个原因） - 但是文档既不确认也不否认这个假设。
进一步深入，Sequence概念的文档说：
priority_queue 使用a 向量（默认情况下）作为堆，其中：
我推断，使用默认 priority_queue ， top（）是 O（1）和 push（）是 O（n）。
问题1：这是正确的吗？ （ top（）访问 O（1）和 push $ c> O（n）？）
问题2：如果我使用了一个集合，则能够在 push（）上实现 O（logn） （或？这样做的后果是什么？其他操作会受到什么影响？ multiset ）而不是向量 c> priority_queue
注意：我担心时间效率，而不是空间。
b $ b优先级队列适配器使用标准库堆算法来阻止和访问队列 - 这是那些算法的复杂性，您应该在文件。
top（）操作显然是O（1），但是你可能想要调用它后调用它（根据）是O（2 * log（N）），push（）是O（log（N）） - / p>
并且从C ++标准，25.6.3.1，push_heap：
和pop_heap：
I have an application (C++) that I think would be well served by an STL priority_queue. The documentation says:
and
I had previously assumed that top() is O(1), and that push() would be a O(logn) (the two reasons I chose the priority_queue in the first place) - but the documentation neither confirms nor denies this assumption.
Digging deeper, the docs for the Sequence concept say:
The priority_queue uses a vector (by default) as a heap, which:
I'm inferring that, using the default priority_queue, top() is O(1) and push() is O(n).
Question 1: Is this correct? (top() access is O(1) and push() is O(n)?)
Question 2: Would I be able to achieve O(logn) efficiency on push() if I used a set (or multiset) instead of a vector for the implementation of the priority_queue? What would the consequences be of doing this? What other operations would suffer as a consequence?
N.B.: I'm worried about time efficiency here, not space.
The priority queue adaptor uses the standard library heap algorithms to buld 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(log(N)) - same source.
And from the C++ Standard, 25.6.3.1, push_heap :
and pop_heap:
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