#include <iostream>
#include <algorithm>
#include <functional>

struct Monster
{
    bool isAlive() const { return false; }
};  

int main()
{
    Monster mon[10];
    
    if( std::none_of(mon, mon + 10, std::mem_fn(&Monster::isAlive)) )
    {
        std::cout << "Killed all Monster\n";
    }
}