Language: C++

#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;

typedef long long ll;

int main(){
    int n, k;
    ll l, r;
    cin >> n >> k >> l >> r;

    int a[n];
    for(int i = 0; i < n; i++)  cin >> a[i];

    int left = n/2;
    int right = n - left;

    vector<ll> va[left+1], vb[right+1];

    for(int i = 0; i < 1<<left; i++){
        ll sum = 0;
        int popcnt = 0;
        for(int j = 0; j < left; j++){
            if(i>>j & 1)    sum += a[j], popcnt++;
        }
        va[popcnt].push_back(sum);
    }

    for(int i = 0; i < 1<<right; i++){
        ll sum = 0;
        int popcnt = 0;
        for(int j = 0; j < right; j++){
            if(i>>j & 1)    sum += a[left+j], popcnt++;
        }
        vb[popcnt].push_back(sum);
    }

    for(int i = 0; i <= left; i++)   sort(va[i].begin(), va[i].end());
    for(int i = 0; i <= right; i++)  sort(vb[i].begin(), vb[i].end());

    ll ans = 0;
    for(int i = 0; i <= left; i++){
        if(i + right < k)   continue;
        if(i > k)   break;

        for(int j = 0; j < va[i].size(); j++){
            ll tmp = va[i][j];
            ans += max(0ll, (upper_bound(vb[k-i].begin(), vb[k-i].end(), r-tmp) - 
                            lower_bound(vb[k-i].begin(), vb[k-i].end(), l-tmp)));
        }
    }

    cout << ans << endl;

    return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:49:23: error: no matching function for call to 'max(long long int, __gnu_cxx::__normal_iterator<long long int*, std::vector<long long int> >::difference_type)'
   49 |             ans += max(0ll, (upper_bound(vb[k-i].begin(), vb[k-i].end(), r-tmp) -
      |                    ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   50 |                             lower_bound(vb[k-i].begin(), vb[k-i].end(), l-tmp)));
      |                             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/14/string:51,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_algobase.h:257:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)'
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
a.cc:49:23: note:   deduced conflicting types for parameter 'const _Tp' ('long long int' and '__gnu_cxx::__normal_iterator<long long int*, std::vector<long long int> >::difference_type' {aka 'long int'})
   49 |             ans += max(0ll, (upper_bound(vb[k-i].begin(), vb[k-i].end(), r-tmp) -
      |                    ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   50 |                             lower_bound(vb[k-i].begin(), vb[k-i].end(), l-tmp)));
      |                             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)'
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/algorithm:61,
                 from a.cc:3:
/usr/include/c++/14/bits/stl_algo.h:5706:5: note: candidate: 'template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)'
 5706 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5706:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5716:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)'
 5716 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5716:5: note:   template argument deduction/substitution failed:
a.cc:49:23: note:   mismatched types 'std::initializer_list<_Tp>' and 'long long int'
   49 |             ans += max(0ll, (upper_bound(vb[k-i].begin(), vb[k-i].end(), r-tmp) -
      |                    ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   50 |                             lower_bound(vb[k-i].begin(), vb[k-i].end(), l-tmp)));
      |                             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~