Language: C++

#pragma GCC optimize("O3")
#pragma GCC target("avx2")
 
#include <vector>
#include <algorithm>
#include <cstdio>
using namespace std;
  
int main(){
    int N;
    long long W,tV=0,tW=0,x=0;
    scanf("%d%lld",&N,&W);
    vector<pair<long long,long long> >v(N);
    for(int i=0;i<N;i++)scanf("%lld%lld",&v[i].first,&v[i].second),tV+=v[i].first,tW+=v[i].second;
 
        int n=N/2;
        vector<pair<long long,long long> >se1,se2;
        for(int i=0;i<1<<n;i++){
            long long V=0,w=0;
            for(int j=0;j<n;j++)if(i&(1<<j))V+=v[j].first,w+=v[j].second;
            se1.emplace_back(w,V);
        }
        for(int i=0;i<1<<(N-n);i++){
            long long V=0,w=0;
            for(int j=0;j<(N-n);j++)if(i&(1<<j))V+=v[j+n].first,w+=v[j+n].second;
            se2.emplace_back(w,V);
        }
sort(se1.begin(),se1.end());
sort(se2.begin(),se2.end());
        for(auto it=se1.begin();it!=se1.end();){
            auto it2=it;
            for(++it2;it2!=se1.end()&&it->second>=it2->second;)it2=se1.erase(it2);
            ++it;
        }
        for(auto it=se2.begin();it!=se2.end();){
            auto it2=it;
            for(++it2;it2!=se2.end()&&it->second>=it2->second;)it2=se2.erase(it2);
            ++it;
        }
        long long r=0;
        for(auto &e1:se1){
            auto it=lower_bound(se2.begin(),se2.end(),make_pair(W-e1.first+1,0));
            if(it!=se2.begin()){
                --it;
                r=max(r,e1.second+it->second);
            }
        }
        printf("%lld\n",r);
}

Compiler output:
In file included from /usr/include/c++/14/bits/stl_algobase.h:71,
                 from /usr/include/c++/14/vector:62,
                 from a.cc:4:
/usr/include/c++/14/bits/predefined_ops.h: In instantiation of 'bool __gnu_cxx::__ops::_Iter_less_val::operator()(_Iterator, _Value&) const [with _Iterator = __gnu_cxx::__normal_iterator<std::pair<long long int, long long int>*, std::vector<std::pair<long long int, long long int> > >; _Value = const std::pair<long long int, int>]':
/usr/include/c++/14/bits/stl_algobase.h:1504:14:   required from '_ForwardIterator std::__lower_bound(_ForwardIterator, _ForwardIterator, const _Tp&, _Compare) [with _ForwardIterator = __gnu_cxx::__normal_iterator<pair<long long int, long long int>*, vector<pair<long long int, long long int> > >; _Tp = pair<long long int, int>; _Compare = __gnu_cxx::__ops::_Iter_less_val]'
 1504 |           if (__comp(__middle, __val))
      |               ~~~~~~^~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:1539:32:   required from '_ForwardIterator std::lower_bound(_ForwardIterator, _ForwardIterator, const _Tp&) [with _ForwardIterator = __gnu_cxx::__normal_iterator<pair<long long int, long long int>*, vector<pair<long long int, long long int> > >; _Tp = pair<long long int, int>]'
 1539 |       return std::__lower_bound(__first, __last, __val,
      |              ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
 1540 |                                 __gnu_cxx::__ops::__iter_less_val());
      |                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
a.cc:42:32:   required from here
   42 |             auto it=lower_bound(se2.begin(),se2.end(),make_pair(W-e1.first+1,0));
      |                     ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/predefined_ops.h:69:22: error: no match for 'operator<' (operand types are 'std::pair<long long int, long long int>' and 'const std::pair<long long int, int>')
   69 |       { return *__it < __val; }
      |                ~~~~~~^~~~~~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:1241:5: note: candidate: 'template<class _IteratorL, class _IteratorR, class _Container> bool __gnu_cxx::operator<(const __normal_iterator<_IteratorL, _Container>&, const __normal_iterator<_IteratorR, _Container>&)'
 1241 |     operator<(const __normal_iterator<_IteratorL, _Container>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1241:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/predefined_ops.h:69:22: note:   'std::pair<long long int, long long int>' is not derived from 'const __gnu_cxx::__normal_iterator<_IteratorL, _Container>'
   69 |       { return *__it < __val; }
      |                ~~~~~~^~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1249:5: note: candidate: 'template<class _Iterator, class _Container> bool __gnu_cxx::operator<(const __normal_iterator<_Iterator, _Container>&, const __normal_iterator<_Iterator, _Container>&)'
 1249 |     operator<(const __normal_iterator<_Iterator, _Container>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1249:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/predefined_ops.h:69:22: note:   'std::pair<long long int, long long int>' is not derived from 'const __gnu_cxx::__normal_iterator<_Iterator, _Container>'
   69 |       { return *__it < __val; }
      |                ~~~~~~^~~~~~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:64:
/usr/include/c++/14/bits/stl_pair.h:1045:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator<(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1045 |     operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1045:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/predefined_ops.h:69:22: note:   deduced conflicting types for parameter '_T2' ('long long int' and 'int')
   69 |       { return *__it < __val; }
      |                ~~~~~~^~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:448:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  448 |     operator<(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:448:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/predefined_ops.h:69:22: note:   'std::pair<long long int, long long int>' is not derived from 'const std::reverse_iterator<_Iterator>'
   69 |       { return *__it < __val; }
      |                ~~~~~~^~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  493 |     operator<(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/predefined_ops.h:69:22: note:   'std::pair<long long int, long long int>' is not derived from 'const std::reverse_iterator<_Iterator>'
   69 |       { return *__it < __val; }
      |                ~~~~~~^~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1694 |     operator<(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/predefined_ops.h:69:22: note:   'std::pair<long long int, long long int>' is not derived from 'const std::move_iterator<_IteratorL>'
   69 |       { return *__it < __val; }
      |                ~~~~~~^~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1760 |     operator<(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/predefined_ops.h:69:22: note:   'std::pair<long long int, long long int>' is not derived from 'const std::move_iterator<_IteratorL>'
   69 |       { return *__it < __val; }
      |                ~~~~~~^~~~~~~
In file included from /usr/include/c++/14/vector:66:
/usr/include/c++/14/bits/stl_vector.h:2089:5: note: candidate: 'template<class _Tp, class _Alloc> bool std::operator<(const vector<_Tp, _Alloc>&, const vector<_Tp, _Alloc>&)'
 2089 |     operator<(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:2089:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/predefined_ops.h:69:22: note:   'std::pair<long long int, long long int>' is not derived from 'const std::vector<_Tp, _Alloc>'
   69 |       { return *__it < __val; }
      |                ~~~~~~^~~~~~~
In file included from /usr/include/c++/14/bits/memory_resource.h:47,
                 from /usr/include/c++/14/vector:87:
/usr/include/c++/14/tuple:2600:5: note: candidate: 'template<class ... _TElements, class ... _UElements> constexpr bool std::operator<(const tuple<_UTypes ...>&, const tuple<_Elements ...>&)'
 2600 |     operator<(const tuple<_TElements...>& __t,
      |     ^~~~~~~~
/usr/include/c++/14/tuple:2600:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/predefined_ops.h:69:22: note:   'std::pair<long long int, long long int>' is not derived from 'const std::tuple<_UTypes ...>'
   69 |       { return *__it < __val; }
      |                ~~~~~~^~~~~~~