Priority queue for user-defined types

c++ priority-queue min-heap
Programmer picture Programmer · Feb 7, 2012 · Viewed 34.7k times · Source

I have the below struct

struct node{
   float val;
   int count;

}

I have several objects of this struct. Now, I want to insert these objects into a priority queue of STL such that the priority queue orders the items by count. Any idea on how to do so? Preferably a min heap is preferred. I know how to do the above for primitive data types, not structs

Answer

Ivaylo Strandjev picture Ivaylo Strandjev · Feb 7, 2012

Overload the < operator:

bool operator<(const node& a, const node& b) {
  return a.count > b.count;
}

I have reversed the comparison to achieve min heap wihtout passing extra arguments to the priority queue. Now you use it like this:

priority_queue<node> pq;
...

Edit: take a look at this post which seems to be almost exact duplicate: STL Priority Queue on custom class

Related questions

Creating Min Heap from STL Priority Queue

I am creating a min heap from stl priority queue. Here is my class which I am using. class Plane { private : int id ; int fuel ; public: Plane():id(0), fuel(0){} Plane(const int _id, const int _fuel):id(_id), fuel(_fuel) {} …

Read More
declaring a priority_queue in c++ with a custom comparator

I'm trying to declare a priority_queue of nodes, using bool Compare(Node a, Node b) as the comparator function (which is outside the node class). What I currently have is: priority_queue<Node, vector<Node>, Compare&…

Read More
How can I create Min stl priority_queue?

The default stl priority queue is a Max one (Top function returns the largest element). Say, for simplicity, that it is a priority queue of int values.

Read More