c ++优先级队列：删除元素不在顶部 [英] c++ priority queue: removing element not at top

问题描述

在我的程序中，我需要从不在顶部的优先级队列中删除一个元素。可以做到吗？

In my program I need to delete an element from a priority queue that is not at the top. Can that be done? If not, please suggest a way to do so except creating your own heap.

推荐答案

标准 priority_queue< ; T> 可以通过继承来定制。它具有可以在后代类中引用的受保护成员 c 和 comp 。

The standard priority_queue<T> can be customized through inheritance. It has protected members c and comp that can be referenced in a descendant class.

template<typename T>
class custom_priority_queue : public std::priority_queue<T, std::vector<T>>
{
  public:

      bool remove(const T& value) {
        auto it = std::find(this->c.begin(), this->c.end(), value);
        if (it != this->c.end()) {
            this->c.erase(it);
            std::make_heap(this->c.begin(), this->c.end(), this->comp);
            return true;
       }
       else {
        return false;
       }
 }
};

void main()
{
   custom_priority_queue<int> queue;

   queue.push(10);
   queue.push(2);
   queue.push(4);
   queue.push(6);
   queue.push(3);

   queue.remove(6);

   while (!queue.empty())
   {
      std::cout << queue.top();
      queue.pop();

      if (!queue.empty())
      {
        std::cout << ", ";
      }
   }

 }

10，4，3，2

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