Language: C++

#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
typedef long long li;
#define rep(i,n) for(int i=0;i<(n);i++)
#define df 0
template<class T> void print(const T& t){ cout << t << "\n"; }
template<class T, class... Ts> void print(const T& t, const Ts&... ts) { cout << t; if (sizeof...(ts)) cout << " "; print(ts...); }
// Container コンテナ型, map以外
template< template<class ...> class Ctn,class T>
std::ostream& operator<<(std::ostream& os,const Ctn<T>& v){
  auto itr=v.begin();
  while(itr!=v.end()){
    if(itr!=v.begin())cout << " ";
    cout << *(itr++);
  }
  return os;
}

int main(){
  int n,k; cin >>n >>k;
  vector<li> v(n); rep(i,n) cin >>v[i];
  if(k>=n*2){
    li s=0;
    for(li x:v) s+=max((li)x,(li)0);
    print(s);
    return 0;
  }
  li m=0;
  rep(d,(k+1)/2){  // dispose
    rep(l,min(k-d,n)+1){
      vector<li> take;
      rep(i,l)take.push_back(v[i]);
      if(df)print("l",take);
      rep(r,min(n-l,k-d-l)+1){
        if(r>0){
          take.push_back(v[n-r]);
        }
        sort(take.begin(),take.end());
        if(df)print(take);
        li s=0;
        rep(i,take.size()){
          if((i>=d) or (take[i]>=0)) s+=take[i];
        }
        m=max(m,s);
      }
    }
  }
  print(m);
}
#define df 0
#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
typedef long long li;
#define rep(i,n) for(int i=0;i<(n);i++)
#define df 0
template<class T> void print(const T& t){ cout << t << "\n"; }
template<class T, class... Ts> void print(const T& t, const Ts&... ts) { cout << t; if (sizeof...(ts)) cout << " "; print(ts...); }
// Container コンテナ型, map以外
template< template<class ...> class Ctn,class T>
std::ostream& operator<<(std::ostream& os,const Ctn<T>& v){
  auto itr=v.begin();
  while(itr!=v.end()){
    if(itr!=v.begin())cout << " ";
    cout << *(itr++);
  }
  return os;
}

int main(){
  int n,k; cin >>n >>k;
  vector<li> v(n); rep(i,n) cin >>v[i];
  if(k>=n*2){
    li s=0;
    for(li x:v) s+=max((li)x,(li)0);
    print(s);
    return 0;
  }
  li m=0;
  rep(d,(k+1)/2){  // dispose
    rep(l,min(k-d,n)+1){
      vector<li> take;
      rep(i,l)take.push_back(v[i]);
      if(df)print("l",take);
      rep(r,min(n-l,k-d-l)+1){
        if(r>0){
          take.push_back(v[n-r]);
        }
        sort(take.begin(),take.end());
        if(df)print(take);
        li s=0;
        rep(i,take.size()){
          if((i>=d) or (take[i]>=0)) s+=take[i];
        }
        m=max(m,s);
      }
    }
  }
  print(m);
}


Compiler output:
a.cc:60:24: error: redefinition of 'template<class T> void print(const T&)'
   60 | template<class T> void print(const T& t){ cout << t << "\n"; }
      |                        ^~~~~
a.cc:8:24: note: 'template<class T> void print(const T&)' previously declared here
    8 | template<class T> void print(const T& t){ cout << t << "\n"; }
      |                        ^~~~~
a.cc:61:37: error: redefinition of 'template<class T, class ... Ts> void print(const T&, const Ts& ...)'
   61 | template<class T, class... Ts> void print(const T& t, const Ts&... ts) { cout << t; if (sizeof...(ts)) cout << " "; print(ts...); }
      |                                     ^~~~~
a.cc:9:37: note: 'template<class T, class ... Ts> void print(const T&, const Ts& ...)' previously declared here
    9 | template<class T, class... Ts> void print(const T& t, const Ts&... ts) { cout << t; if (sizeof...(ts)) cout << " "; print(ts...); }
      |                                     ^~~~~
a.cc:64:15: error: redefinition of 'template<template<class ...> class Ctn, class T> std::ostream& operator<<(std::ostream&, const Ctn<T>&)'
   64 | std::ostream& operator<<(std::ostream& os,const Ctn<T>& v){
      |               ^~~~~~~~
a.cc:12:15: note: 'template<template<class ...> class Ctn, class T> std::ostream& operator<<(std::ostream&, const Ctn<T>&)' previously declared here
   12 | std::ostream& operator<<(std::ostream& os,const Ctn<T>& v){
      |               ^~~~~~~~
a.cc:73:5: error: redefinition of 'int main()'
   73 | int main(){
      |     ^~~~
a.cc:21:5: note: 'int main()' previously defined here
   21 | int main(){
      |     ^~~~
a.cc: In instantiation of 'void print(const T&) [with T = std::vector<long long int>]':
a.cc:41:20:   required from here
   41 |         if(df)print(take);
      |               ~~~~~^~~~~~
a.cc:8:48: error: no match for 'operator<<' (operand types are 'std::ostream' {aka 'std::basic_ostream<char>'} and 'const std::vector<long long int>')
    8 | template<class T> void print(const T& t){ cout << t << "\n"; }
      |                                           ~~~~~^~~~
In file included from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/ostream:116:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(__ostream_type& (*)(__ostream_type&)) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  116 |       operator<<(__ostream_type& (*__pf)(__ostream_type&))
      |       ^~~~~~~~
/usr/include/c++/14/ostream:116:36: note:   no known conversion for argument 1 from 'const std::vector<long long int>' to 'std::basic_ostream<char>::__ostream_type& (*)(std::basic_ostream<char>::__ostream_type&)' {aka 'std::basic_ostream<char>& (*)(std::basic_ostream<char>&)'}
  116 |       operator<<(__ostream_type& (*__pf)(__ostream_type&))
      |                  ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/ostream:125:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(__ios_type& (*)(__ios_type&)) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>; __ios_type = std::basic_ios<char>]'
  125 |       operator<<(__ios_type& (*__pf)(__ios_type&))
      |       ^~~~~~~~
/usr/include/c++/14/ostream:125:32: note:   no known conversion for argument 1 from 'const std::vector<long long int>' to 'std::basic_ostream<char>::__ios_type& (*)(std::basic_ostream<char>::__ios_type&)' {aka 'std::basic_ios<char>& (*)(std::basic_ios<char>&)'}
  125 |       operator<<(__ios_type& (*__pf)(__ios_type&))
      |                  ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
/usr/include/c++/14/ostream:135:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::ios_base& (*)(std::ios_base&)) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  135 |       operator<<(ios_base& (*__pf) (ios_base&))
      |       ^~~~~~~~
/usr/include/c++/14/ostream:135:30: note:   no known conversion for argument 1 from 'const std::vector<long long int>' to 'std::ios_base& (*)(std::ios_base&)'
  135 |       operator<<(ios_base& (*__pf) (ios_base&))
      |                  ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
/usr/include/c++/14/ostream:174:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long int) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  174 |       operator<<(long __n)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:174:23: note:   no known conversion for argument 1 from 'const std::vector<long long int>' to 'long int'
  174 |       operator<<(long __n)
      |                  ~~~~~^~~
/usr/include/c++/14/ostream:178:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  178 |       operator<<(unsigned long __n)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:178:32: note:   no known conversion for argument 1 from 'const std::vector<long long int>' to 'long unsigned int'
  178 |       operator<<(unsigned long __n)
      |                  ~~~~~~~~~~~~~~^~~
/usr/include/c++/14/ostream:182:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(bool) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  182 |       operator<<(bool __n)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:182:23: note:   no known conversion for argument 1 from 'const std::vector<long long int>' to 'bool'
  182 |       operator<<(bool __n)
      |                  ~~~~~^~~
In file included from /usr/include/c++/14/ostream:1022:
/usr/include/c++/14/bits/ostream.tcc:96:5: note: candidate: 'std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(short int) [with _CharT = char; _Traits = std::char_traits<char>]'
   96 |     basic_ostream<_CharT, _Traits>::
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/ostream.tcc:97:22: note:   no known conversion for argument 1 from 'const std::vector<long long int>' to 'short int'
   97 |     operator<<(short __n)
      |                ~~~~~~^~~
/usr/include/c++/14/ostream:189:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(short unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  189 |       operator<<(unsigned short __n)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:189:33: note:   no known conversion for argument 1 from 'const std::vector<long long int>' to 'short unsigned int'
  189 |       operator<<(unsigned short __n)
      |                  ~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/ostream.tcc:110:5: note: candidate: 'std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(int) [with _CharT = char; _Traits = std::char_traits<char>]'
  110 |     basic_ostream<_CharT, _Traits>::
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/ostream.tcc:111:20: note:   no known conversion for argument 1 from 'const std::vector<long long int>' to 'int'
  111 |     operator<<(int __n)
      |                ~~~~^~~
/usr/include/c++/14/ostream:200:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  200 |       operator<<(unsigned int __n)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:200:31: note:   no known conversion for argument 1 from 'const std::vector<long long int>' to 'unsigned int'
  200 |       operator<<(unsigned int __n)
      |                  ~~~~~~~~~~~~~^~~
/usr/include/c++/14/ostream:211:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long int) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  211 |       operator<<(long long __n)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:211:28: note:   no known conversion for argument 1 from 'const std::vector<long long int>' to 'long long int'
  211 |       operator<<(long long __n)
      |                  ~~~~~~~~~~^~~
/usr/include/c++/14/ostream:215:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  215 |       operator<<(unsigned long long __n)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:215:37: note:   no known conversion for argument 1 from 'const std::vector<long long int>' to 'long long unsigned int'
  215 |       operator<<(unsigned long long __n)
      |                  ~~~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/ostream:231:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(double) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  231 |       operator<<(double __f)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:231:25: note:   no known conversion for argument 1 from 'const std::vector<long long int>' to 'double'
  231 |       operator<<(double __f)
      |                  ~~~~~~~^~~
/usr/include/c++/14/ostream:235:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(float) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  235 |       operator<<(float __f)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:235:24: note:   no known conver