#include <set>
struct A
{
	int i;
	int j;
	bool operator<(A const &ref)const
	{
		return i < ref.i;
	}
	bool operator==(A const &ref)const
	{
		return i == ref.i && j == ref.j;
	}
};
int main()
{
	A val1 = {1, 2};
	A val2 = {2, 2};
	std::set<A> my_set;
	my_set.insert(val1);
	my_set.insert(val2);
}

std::set自定义比较函数