C++ STL--make_heap with pair<int,string> as data type

问题

I know how does heap work and how it arranges min and max elements. It is easy, if vector contains only int, to apply make_heap in STL. But how to apply make_heap() if vector contains structure of string and int. Iwant to make heap based on int value in structure. Please tell me how to do that.

回答1:

You have to provide comparison function for your structure:

struct A
{
 int x, y;
};

struct Comp
{
   bool operator()(const A& s1, const A& s2)
   {
       return s1.x < s2.x && s1.y == s2.y;
   }
};

std::vector<A> vec;
std::make_heap(vec.begin(), vec.end(), Comp());

回答2:

Yes, you can use std::make_heap with std::pair<int, std::string> directly because std::pair has the required less-than comparison operator<. There is even an example in the reference linked above using that particular instantiation of std::pair.

来源：https://stackoverflow.com/questions/13190269/c-stl-make-heap-with-pairint-string-as-data-type