Language: C++

# include <bits/stdc++.h>
# define rep(i, n) for(int i=0, i##_len=(n); i<i##_len; ++i)
# define reps(i, n) for(int i=1, i##_len=(n); i<=i##_len; ++i)
# define rrep(i, n) for(int i=((int)(n)-1); i>=0; --i)
# define rreps(i, n) for(int i=((int)(n)); i>0; --i)
# define ALL(x) (x).begin(), (x).end()
# define SZ(x) ((int)(x).size())
# define pb push_back
# define optimize_cin() cin.tie(0); ios::sync_with_stdio(false)
using namespace std;
using lint = long long;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

int main() {
  int N;
  cin >> N;
  int X[N];
  rep(i, N) {
    cin >> X[i];
  }
  int Y[N];
  rep(i, N) {
    rep(j, N) {
       Y[i] += (X[j] - [i + 1]) * (A[j] - [i + 1]);
    }
  }
  ALL(Y);
  cout << Y[N - 1] << endl;
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:25:26: error: expected ',' before '+' token
   25 |        Y[i] += (X[j] - [i + 1]) * (A[j] - [i + 1]);
      |                          ^~
      |                          ,
a.cc:25:27: error: expected identifier before '+' token
   25 |        Y[i] += (X[j] - [i + 1]) * (A[j] - [i + 1]);
      |                           ^
a.cc: In lambda function:
a.cc:25:31: error: expected '{' before ')' token
   25 |        Y[i] += (X[j] - [i + 1]) * (A[j] - [i + 1]);
      |                               ^
a.cc: In function 'int main()':
a.cc:25:22: error: no match for 'operator-' (operand types are 'int' and 'main()::<lambda()>')
   25 |        Y[i] += (X[j] - [i + 1]) * (A[j] - [i + 1]);
      |                 ~~~~ ^ ~~~~~~~
      |                    |   |
      |                    int main()::<lambda()>
In file included from /usr/include/c++/14/bits/stl_algobase.h:67,
                 from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_iterator.h:618:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr decltype ((__y.base() - __x.base())) std::operator-(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  618 |     operator-(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:618:5: note:   template argument deduction/substitution failed:
a.cc:25:31: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'int'
   25 |        Y[i] += (X[j] - [i + 1]) * (A[j] - [i + 1]);
      |                               ^
/usr/include/c++/14/bits/stl_iterator.h:1790:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr decltype ((__x.base() - __y.base())) std::operator-(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1790 |     operator-(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1790:5: note:   template argument deduction/substitution failed:
a.cc:25:31: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'int'
   25 |        Y[i] += (X[j] - [i + 1]) * (A[j] - [i + 1]);
      |                               ^
In file included from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127:
/usr/include/c++/14/complex:370:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator-(const complex<_Tp>&, const complex<_Tp>&)'
  370 |     operator-(const complex<_Tp>& __x, const complex<_Tp>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:370:5: note:   template argument deduction/substitution failed:
a.cc:25:31: note:   mismatched types 'const std::complex<_Tp>' and 'int'
   25 |        Y[i] += (X[j] - [i + 1]) * (A[j] - [i + 1]);
      |                               ^
/usr/include/c++/14/complex:379:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator-(const complex<_Tp>&, const _Tp&)'
  379 |     operator-(const complex<_Tp>& __x, const _Tp& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:379:5: note:   template argument deduction/substitution failed:
a.cc:25:31: note:   mismatched types 'const std::complex<_Tp>' and 'int'
   25 |        Y[i] += (X[j] - [i + 1]) * (A[j] - [i + 1]);
      |                               ^
/usr/include/c++/14/complex:388:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator-(const _Tp&, const complex<_Tp>&)'
  388 |     operator-(const _Tp& __x, const complex<_Tp>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:388:5: note:   template argument deduction/substitution failed:
a.cc:25:31: note:   'main()::<lambda()>' is not derived from 'const std::complex<_Tp>'
   25 |        Y[i] += (X[j] - [i + 1]) * (A[j] - [i + 1]);
      |                               ^
/usr/include/c++/14/complex:465:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator-(const complex<_Tp>&)'
  465 |     operator-(const complex<_Tp>& __x)
      |     ^~~~~~~~
/usr/include/c++/14/complex:465:5: note:   candidate expects 1 argument, 2 provided
In file included from /usr/include/c++/14/valarray:605,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:166:
/usr/include/c++/14/bits/valarray_after.h:406:5: note: candidate: 'template<class _Dom1, class _Dom2> std::_Expr<std::__detail::_BinClos<std::__minus, std::_Expr, std::_Expr, _Dom1, _Dom2>, typename std::__fun<std::__minus, typename _Dom1::value_type>::result_type> std::operator-(const _Expr<_Dom1, typename _Dom1::value_type>&, const _Expr<_Dom2, typename _Dom2::value_type>&)'
  406 |     _DEFINE_EXPR_BINARY_OPERATOR(-, struct std::__minus)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:406:5: note:   template argument deduction/substitution failed:
a.cc:25:31: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'int'
   25 |        Y[i] += (X[j] - [i + 1]) * (A[j] - [i + 1]);
      |                               ^
/usr/include/c++/14/bits/valarray_after.h:406:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__minus, std::_Expr, std::_Constant, _Dom, typename _Dom::value_type>, typename std::__fun<std::__minus, typename _Dom1::value_type>::result_type> std::operator-(const _Expr<_Dom1, typename _Dom1::value_type>&, const typename _Dom::value_type&)'
  406 |     _DEFINE_EXPR_BINARY_OPERATOR(-, struct std::__minus)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:406:5: note:   template argument deduction/substitution failed:
a.cc:25:31: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'int'
   25 |        Y[i] += (X[j] - [i + 1]) * (A[j] - [i + 1]);
      |                               ^
/usr/include/c++/14/bits/valarray_after.h:406:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__minus, std::_Constant, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__minus, typename _Dom1::value_type>::result_type> std::operator-(const typename _Dom::value_type&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  406 |     _DEFINE_EXPR_BINARY_OPERATOR(-, struct std::__minus)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:406:5: note:   template argument deduction/substitution failed:
a.cc:25:31: note:   'main()::<lambda()>' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   25 |        Y[i] += (X[j] - [i + 1]) * (A[j] - [i + 1]);
      |                               ^
/usr/include/c++/14/bits/valarray_after.h:406:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__minus, std::_Expr, std::_ValArray, _Dom, typename _Dom::value_type>, typename std::__fun<std::__minus, typename _Dom1::value_type>::result_type> std::operator-(const _Expr<_Dom1, typename _Dom1::value_type>&, const valarray<typename _Dom::value_type>&)'
  406 |     _DEFINE_EXPR_BINARY_OPERATOR(-, struct std::__minus)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:406:5: note:   template argument deduction/substitution failed:
a.cc:25:31: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'int'
   25 |        Y[i] += (X[j] - [i + 1]) * (A[j] - [i + 1]);
      |                               ^
/usr/include/c++/14/bits/valarray_after.h:406:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__minus, std::_ValArray, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__minus, typename _Dom1::value_type>::result_type> std::operator-(const valarray<typename _Dom::value_type>&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  406 |     _DEFINE_EXPR_BINARY_OPERATOR(-, struct std::__minus)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:406:5: note:   template argument deduction/substitution failed:
a.cc:25:31: note:   'main()::<lambda()>' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   25 |        Y[i] += (X[j] - [i + 1]) * (A[j] - [i + 1]);
      |                               ^
/usr/include/c++/14/valarray:1197:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__minus, std::_ValArray, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__minus, _Tp>::result_type> std::operator-(const valarray<_Tp>&, const valarray<_Tp>&)'
 1197 | _DEFINE_BINARY_OPERATOR(-, __minus)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1197:1: note:   template argument deduction/substitution failed:
a.cc:25:31: note:   mismatched types 'const std::valarray<_Tp>' and 'int'
   25 |        Y[i] += (X[j] - [i + 1]) * (A[j] - [i + 1]);
      |                               ^
/usr/include/c++/14/valarray:1197:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__minus, std::_ValArray, std::_Constant, _Tp, _Tp>, typename std::__fun<std::__minus, _Tp>::result_type> std::operator-(const valarray<_Tp>&, const typename valarray<_Tp>::value_type&)'
 1197 | _DEFINE_BINARY_OPERATOR(-, __minus)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1197:1: note:   template argument deduction/substitution failed:
a.cc:25:31: note:   mismatched types 'const std::valarray<_Tp>' and 'int'
   25 |        Y[i] += (X[j] - [i + 1]) * (A[j] - [i + 1]);
      |                               ^
/usr/include/c++/14/valarray:1197:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__minus, std::_Constant, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__minus, _Tp>::result_type> std::operator-(const typename valarray<_Tp>::value_type&, const valarray<_Tp>&)'
 1197 | _DEFINE_BINARY_OPERATOR(-, __minus)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1197:1: note:   template argument deduction/substitution failed:
a.cc:25:31: note:   'main()::<lambda()>' is not derived from 'const std::valarray<_Tp>'
   25 |        Y[i] += (X[j] - [i + 1]) * (A[j] - [i + 1]);