不是優先級隊列的已排序容器

Question

我們需要一個容器，在添加新元素時，該容器可以按元素的優先級對元素進行排序，並且能夠根據給定的ID來檢索元素。

（優先級隊列的問題是它不能讓您根據ID而不是優先級來檢索元素）

謝謝

Answer 1

boost多索引容器使您能夠具有優先級的排序視圖和ID的排序視圖。

一個小例子：

#include <boost/multi_index_container.hpp>
#include <boost/multi_index/ordered_index.hpp>
#include <boost/multi_index/member.hpp>
#include <iostream>
#include <vector>
#include <cstddef>
#include <iterator>

struct elem {
  std::size_t id;
  int priority;
};

int main()
{
  using namespace boost::multi_index;

  typedef multi_index_container<
  elem,
  indexed_by<
    ordered_unique<member<elem,std::size_t,&elem::id> >,
    ordered_non_unique<member<elem,int,&elem::priority> >
    >
  > elem_container;


  // just for show
  std::vector<elem> elems = 
    {{0, 25}, 
     {1, 10}, 
     {2, 100}, 
     {3, 6}
    };
  elem_container elemc(begin(elems), end(elems));
  // by id
  std::cout << "By ID: " << std::endl;
  for(auto& x : elemc.get<0>()) { 
    std::cout << "id: " << x.id << "priority: " << x.priority << std::endl;
  }

  // by priority
  std::cout << "By Priority: " << std::endl;
  for(auto& x : elemc.get<1>()) { 
    std::cout << "id: " << x.id << "priority: " << x.priority << std::endl;
  }
  return 0;
}