Question

I have a Node class with the members

int weight;
Node *left;
Node *right;

I want to create a heap by using the STL functions

make_heap(Iterator , Iterator, comp) 
pop_heap(Iterator, Iterator, comp)

to apply on a vector of Node pointers. How can I create a comparison object (or comparison function) for those functions?

Answer 1

If you provide strict weak ordering via a operator< for your object you can call the overload of make_heap, pop_heap, etc which don’t even need the third argument. comp is so you can provide a custom comparison if you choose.

class Node
{
int weight;
Node *left;
Node *right;

public:
bool operator<(const Node& rhs) const { return weight < rhs.weight; }
};