Language: C++

#include <iostream>
#include <algorithm>
#include <vector>

#define max(a,b) ((a)>(b)?(a):(b))

typedef long long LL;

int main(){
  int n,p,q;
  cin >> n >> p >> q;
  vector<int> c(n);
  for(int i=0;i<n;i++){
    cin >> c[i];
    c[i]+=i*p;
  }
  sort(c.begin(),c.end(),greater<int>());
  LL ans=(q*n+n*(n-1)/2)*p;
  LL ruiseki=0;
  for(int i=0;i<n;i++){
    ruseki+=c[i];
    ans=max(ans,ruiseki+(q*(i+1)+(n-i-2)*(n-i-1))*p-(n*(n-1)/2)*p);
  }
  cout << ans << endl;
  return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:11:3: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
   11 |   cin >> n >> p >> q;
      |   ^~~
      |   std::cin
In file included from a.cc:1:
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:12:3: error: 'vector' was not declared in this scope
   12 |   vector<int> c(n);
      |   ^~~~~~
a.cc:12:3: note: suggested alternatives:
In file included from /usr/include/c++/14/vector:66,
                 from a.cc:3:
/usr/include/c++/14/bits/stl_vector.h:428:11: note:   'std::vector'
  428 |     class vector : protected _Vector_base<_Tp, _Alloc>
      |           ^~~~~~
/usr/include/c++/14/vector:93:13: note:   'std::pmr::vector'
   93 |       using vector = std::vector<_Tp, polymorphic_allocator<_Tp>>;
      |             ^~~~~~
a.cc:12:10: error: expected primary-expression before 'int'
   12 |   vector<int> c(n);
      |          ^~~
a.cc:14:12: error: 'c' was not declared in this scope
   14 |     cin >> c[i];
      |            ^
a.cc:17:8: error: 'c' was not declared in this scope
   17 |   sort(c.begin(),c.end(),greater<int>());
      |        ^
a.cc:17:26: error: 'greater' was not declared in this scope; did you mean 'std::greater'?
   17 |   sort(c.begin(),c.end(),greater<int>());
      |                          ^~~~~~~
      |                          std::greater
In file included from /usr/include/c++/14/string:49,
                 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:
/usr/include/c++/14/bits/stl_function.h:353:12: note: 'std::greater' declared here
  353 |     struct greater;
      |            ^~~~~~~
a.cc:17:34: error: expected primary-expression before 'int'
   17 |   sort(c.begin(),c.end(),greater<int>());
      |                                  ^~~
a.cc:17:3: error: 'sort' was not declared in this scope; did you mean 'std::sort'?
   17 |   sort(c.begin(),c.end(),greater<int>());
      |   ^~~~
      |   std::sort
In file included from /usr/include/c++/14/algorithm:86,
                 from a.cc:2:
/usr/include/c++/14/pstl/glue_algorithm_defs.h:296:1: note: 'std::sort' declared here
  296 | sort(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last);
      | ^~~~
a.cc:21:5: error: 'ruseki' was not declared in this scope; did you mean 'ruiseki'?
   21 |     ruseki+=c[i];
      |     ^~~~~~
      |     ruiseki
a.cc:24:3: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   24 |   cout << ans << endl;
      |   ^~~~
      |   std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:24:18: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   24 |   cout << ans << endl;
      |                  ^~~~
      |                  std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~