partial_sort

#include <algorithm>
#include <iostream>
#include <vector>
                                                                                                                
using std::vector,
    std::partial_sort,
    std::cerr;
                                        
class Temp{
    public:
        int a, b;
        Temp(int i, int j):a(i), b(j){}
        bool operator < (Temp t){
            if(this->a < t.a && this->b < t.b){
                return true;
            }
            return false;
        }
};

typedef vector<Temp> my_vector;
            
int main(){
    my_vector a = {Temp(16, 256), Temp(4, 16), Temp(12, 144), Temp(4, 16), Temp(19, 361), Temp(9, 81), Temp(3, 9), Temp(15, 225), Temp(5, 25), Temp(6, 36), Temp(1, 1), Temp(8, 64), Temp(13, 169), Temp(0, 0), Temp(2, 4), Temp(2, 4), Temp(3, 9), Temp(10, 100), Temp(18, 324), Temp(14, 196), Temp(17, 289), Temp(7, 49), Temp(11, 121)};
    auto print = [] (Temp t){
        cerr << "Temp(" << t.a << ", " << t.b << ")\n";
    }; 

    my_vector::iterator middle = a.begin();
    advance(middle, 10);

    partial_sort(a.begin(), middle, a.end());
    cerr << "a after partial_sort:\n";
    for_each(a.begin(), a.end(), print);

    auto test = [] (Temp a, Temp b)->bool{
        if(a.a < b.a && a.b < b.b){
            return true;
        }
        return false;
    };

    my_vector b = {Temp(16, 256), Temp(4, 16), Temp(12, 144), Temp(4, 16), Temp(19, 361), Temp(9, 81), Temp(3, 9), Temp(15, 225), Temp(5, 25), Temp(6, 36), Temp(1, 1), Temp(8, 64), Temp(13, 169), Temp(0, 0), Temp(2, 4), Temp(2, 4), Temp(3, 9), Temp(10, 100), Temp(18, 324), Temp(14, 196), Temp(17, 289), Temp(7, 49), Temp(11, 121)};
    middle = b.begin();
    advance(middle, 10);

    partial_sort(b.begin(), middle, b.end(), test);

    cerr << "b after partial_sort:\n";
    for_each(b.begin(), b.end(), print);
    return 0;
}