C++ 优先级队列不排序

Question

I tried to implement a priority queue in C++ with a custom Class and Compare struct, but whenever I push a new element the queue doesn´t sort itself.

In Header:

private:
    std::priority_queue<Node*, std::vector<Node*>, NodeCompare> queue;

Struct:

struct NodeCompare
{
    bool operator()(Node* n1, Node* n2) 
    {
        int val1 = n1->getValue();
        int val2 = n2->getValue();
        return val1 < val2;
    }
};

In Class:

Node* node = new Node(nrInTree, value);
queue.push_back(node);

Any ideas?

Answer 1

Your code is correct. But I think you have a misunderstanding here. Because priority_queue is implemented using data structure heap. As we know, heap is not sorted. It only has the property that the maximum element is at the front. Every time, you insert an element into a heap, heap will use O(lgN) time to push the maximum into the front. And every time you pop an element, the largest element will be obtained. But heap is not sorted at all.