| # | 제출 시각 | 아이디 | 문제 | 언어 | 결과 | 실행 시간 | 메모리 |
|---|---|---|---|---|---|---|---|
| 1280821 | lalbertoo89 | 콤보 (IOI18_combo) | C++20 | 컴파일 에러 | 0 ms | 0 KiB |
#include <bits/stdc++.h>
using namespace std;
#include "combo.h"
string guess_sequence(int N){
string buttons = "ABXY";
string S = "";
string first;
for(char c : buttons){
if(press(string(1, c)) > 0){
first = c;
break;
}
}
S += first;
string s1 = "";
for(char c : buttons){
if(c != first) s1 += c;
}
while((int)S.size() < N - 1){
int k = S.size();
string s2 = "";
s2 += S + s1[0] + s1[0];
s2 += S + s1[0] + s1[1];
s2 += S + s1[0] + s1[2];
int luis = press(s2);
if(luis == k) S += s1[2];
else if(luis == k + 1) S += s1[1];
else S += s1[0];
}
if((int)S.size() < N){
for(char c : s1){
if(press(S + c) == N){
S += c;
break;
}
}
}
return S;
}
컴파일 시 표준 에러 (stderr) 메시지
combo.cpp: In function 'std::string guess_sequence(int)':
combo.cpp:20:14: error: no match for 'operator!=' (operand types are 'char' and 'std::string' {aka 'std::__cxx11::basic_string<char>'})
20 | if(c != first) s1 += c;
| ~ ^~ ~~~~~
| | |
| char std::string {aka std::__cxx11::basic_string<char>}
In file included from /usr/include/c++/13/regex:68,
from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:181,
from combo.cpp:1:
/usr/include/c++/13/bits/regex.h:1274:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator==(const sub_match<_BiIter>&, __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&)' (reversed)
1274 | operator==(const sub_match<_Bi_iter>& __lhs,
| ^~~~~~~~
/usr/include/c++/13/bits/regex.h:1274:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/bits/regex.h:1441:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)' (reversed)
1441 | operator==(const sub_match<_Bi_iter>& __lhs,
| ^~~~~~~~
/usr/include/c++/13/bits/regex.h:1441:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/bits/regex.h:1613:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)' (reversed)
1613 | operator==(const sub_match<_Bi_iter>& __lhs,
| ^~~~~~~~
/usr/include/c++/13/bits/regex.h:1613:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/bits/stl_algobase.h:67,
from /usr/include/c++/13/algorithm:60,
from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:51:
/usr/include/c++/13/bits/stl_iterator.h:534:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const reverse_iterator<_IteratorL>&, const reverse_iterator<_IteratorR>&) requires requires{{std::operator==::__x->base() == std::operator==::__y->base()} -> decltype(auto) [requires std::convertible_to<<placeholder>, bool>];}' (reversed)
534 | operator==(const reverse_iterator<_IteratorL>& __x,
| ^~~~~~~~
/usr/include/c++/13/bits/stl_iterator.h:534:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::reverse_iterator<_IteratorL>'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/bits/stl_iterator.h:1678:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&) requires requires{{std::operator==::__x->base() == std::operator==::__y->base()} -> decltype(auto) [requires std::convertible_to<<placeholder>, bool>];}' (reversed)
1678 | operator==(const move_iterator<_IteratorL>& __x,
| ^~~~~~~~
/usr/include/c++/13/bits/stl_iterator.h:1678:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::move_iterator<_IteratorL>'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/string:43,
from /usr/include/c++/13/bitset:52,
from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:52:
/usr/include/c++/13/bits/allocator.h:237:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator==(const allocator<_CharT>&, const allocator<_T2>&)' (reversed)
237 | operator==(const allocator<_T1>&, const allocator<_T2>&)
| ^~~~~~~~
/usr/include/c++/13/bits/allocator.h:237:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::allocator<_CharT>'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/bits/basic_string.h:47,
from /usr/include/c++/13/string:54:
/usr/include/c++/13/string_view:616:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator==(basic_string_view<_CharT, _Traits>, __type_identity_t<basic_string_view<_CharT, _Traits> >)' (reversed)
616 | operator==(basic_string_view<_CharT, _Traits> __x,
| ^~~~~~~~
/usr/include/c++/13/string_view:616:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::__cxx11::basic_string<char>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/bits/basic_string.h:3727:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> constexpr bool std::operator==(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const _CharT*)' (reversed)
3727 | operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
| ^~~~~~~~
/usr/include/c++/13/bits/basic_string.h:3727:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const _CharT*' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/bits/uses_allocator_args.h:38,
from /usr/include/c++/13/bits/memory_resource.h:41,
from /usr/include/c++/13/string:58:
/usr/include/c++/13/tuple:1919:5: note: candidate: 'template<class ... _TElements, class ... _UElements> constexpr bool std::operator==(const tuple<_UTypes ...>&, const tuple<_UTypes ...>&)' (reversed)
1919 | operator==(const tuple<_TElements...>& __t,
| ^~~~~~~~
/usr/include/c++/13/tuple:1919:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::tuple<_UTypes ...>'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/functional:59,
from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:53:
/usr/include/c++/13/bits/std_function.h:737:5: note: candidate: 'template<class _Res, class ... _Args> bool std::operator==(const function<_Res(_ArgTypes ...)>&, nullptr_t)' (reversed)
737 | operator==(const function<_Res(_Args...)>& __f, nullptr_t) noexcept
| ^~~~~~~~
/usr/include/c++/13/bits/std_function.h:737:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::function<_Res(_ArgTypes ...)>'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/memory:78,
from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:56:
/usr/include/c++/13/bits/unique_ptr.h:829:5: note: candidate: 'template<class _Tp, class _Dp, class _Up, class _Ep> bool std::operator==(const unique_ptr<_Tp, _Dp>&, const unique_ptr<_Up, _Ep>&)' (reversed)
829 | operator==(const unique_ptr<_Tp, _Dp>& __x,
| ^~~~~~~~
/usr/include/c++/13/bits/unique_ptr.h:829:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::unique_ptr<_Tp, _Dp>'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/bits/unique_ptr.h:837:5: note: candidate: 'template<class _Tp, class _Dp> bool std::operator==(const unique_ptr<_Tp, _Dp>&, nullptr_t)' (reversed)
837 | operator==(const unique_ptr<_Tp, _Dp>& __x, nullptr_t) noexcept
| ^~~~~~~~
/usr/include/c++/13/bits/unique_ptr.h:837:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::unique_ptr<_Tp, _Dp>'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/bits/shared_ptr.h:53,
from /usr/include/c++/13/memory:80:
/usr/include/c++/13/bits/shared_ptr_base.h:1793:5: note: candidate: 'template<class _Tp1, class _Tp2, __gnu_cxx::_Lock_policy _Lp> bool std::operator==(const __shared_ptr<_Tp1, _Lp>&, const __shared_ptr<_Tp2, _Lp>&)' (reversed)
1793 | operator==(const __shared_ptr<_Tp1, _Lp>& __a,
| ^~~~~~~~
/usr/include/c++/13/bits/shared_ptr_base.h:1793:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__shared_ptr<_Tp1, _Lp>'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/bits/shared_ptr_base.h:1799:5: note: candidate: 'template<class _Tp, __gnu_cxx::_Lock_policy _Lp> bool std::operator==(const __shared_ptr<_Tp, _Lp>&, nullptr_t)' (reversed)
1799 | operator==(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
| ^~~~~~~~
/usr/include/c++/13/bits/shared_ptr_base.h:1799:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__shared_ptr<_Tp, _Lp>'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/bits/shared_ptr.h:555:5: note: candidate: 'template<class _Tp, class _Up> bool std::operator==(const shared_ptr<_Tp>&, const shared_ptr<_Tp>&)' (reversed)
555 | operator==(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
| ^~~~~~~~
/usr/include/c++/13/bits/shared_ptr.h:555:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::shared_ptr<_Tp>'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/bits/shared_ptr.h:561:5: note: candidate: 'template<class _Tp> bool std::operator==(const shared_ptr<_Tp>&, nullptr_t)' (reversed)
561 | operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
| ^~~~~~~~
/usr/include/c++/13/bits/shared_ptr.h:561:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::shared_ptr<_Tp>'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:67:
/usr/include/c++/13/scoped_allocator:505:5: note: candidate: 'template<class _OutA1, class _OutA2, class ... _InA> bool std::operator==(const scoped_allocator_adaptor<_OutA1, _InA ...>&, const scoped_allocator_adaptor<_InnerHead, _InnerTail ...>&)' (reversed)
505 | operator==(const scoped_allocator_adaptor<_OutA1, _InA...>& __a,
| ^~~~~~~~
/usr/include/c++/13/scoped_allocator:505:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::scoped_allocator_adaptor<_OutA1, _InA ...>'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:79:
/usr/include/c++/13/optional:1296:5: note: candidate: 'template<class _Tp> constexpr bool std::operator==(const optional<_Tp>&, nullopt_t)' (reversed)
1296 | operator==(const optional<_Tp>& __lhs, nullopt_t) noexcept
| ^~~~~~~~
/usr/include/c++/13/optional:1296:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::optional<_Tp>'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/ccomplex:39,
from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:127:
/usr/include/c++/13/complex:472:5: note: candidate: 'template<class _Tp> constexpr bool std::operator==(const complex<_Tp>&, const _Tp&)' (reversed)
472 | operator==(const complex<_Tp>& __x, const _Tp& __y)
| ^~~~~~~~
/usr/include/c++/13/complex:472:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::complex<_Tp>'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/x86_64-linux-gnu/c++/13/bits/c++allocator.h:33,
from /usr/include/c++/13/bits/allocator.h:46:
/usr/include/c++/13/bits/new_allocator.h:215:9: note: candidate: 'template<class _Up> constexpr bool std::operator==(const __new_allocator<char>&, const __new_allocator<_Tp>&)' (reversed)
215 | operator==(const __new_allocator&, const __new_allocator<_Up>&)
| ^~~~~~~~
/usr/include/c++/13/bits/new_allocator.h:215:9: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::__new_allocator<_Tp>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/bits/ios_base.h:46,
from /usr/include/c++/13/streambuf:43,
from /usr/include/c++/13/bits/streambuf_iterator.h:35,
from /usr/include/c++/13/iterator:66,
from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:54:
/usr/include/c++/13/system_error:465:3: note: candidate: 'bool std::operator==(const error_code&, const error_condition&)' (reversed)
465 | operator==(const error_code& __lhs, const error_condition& __rhs) noexcept
| ^~~~~~~~
/usr/include/c++/13/system_error:465:32: note: no known conversion for argument 1 from 'std::string' {aka 'std::__cxx11::basic_string<char>'} to 'const std::error_code&'
465 | operator==(const error_code& __lhs, const error_condition& __rhs) noexcept
| ~~~~~~~~~~~~~~~~~~^~~~~
/usr/include/c++/13/bits/regex.h:1103:5: note: candidate: 'template<class _BiIter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const sub_match<_BiIter>&)' (rewritten)
1103 | operator==(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
| ^~~~~~~~
/usr/include/c++/13/bits/regex.h:1103:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/bits/regex.h:2186:5: note: candidate: 'template<class _Bi_iter, class _Alloc> bool std::__cxx11::operator==(const match_results<_BiIter, _Alloc>&, const match_results<_BiIter, _Alloc>&)' (rewritten)
2186 | operator==(const match_results<_Bi_iter, _Alloc>& __m1,
| ^~~~~~~~
/usr/include/c++/13/bits/regex.h:2186:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::__cxx11::match_results<_BiIter, _Alloc>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/bits/stl_algobase.h:64:
/usr/include/c++/13/bits/stl_pair.h:812:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator==(const pair<_T1, _T2>&, const pair<_T1, _T2>&)' (rewritten)
812 | operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
| ^~~~~~~~
/usr/include/c++/13/bits/stl_pair.h:812:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::pair<_T1, _T2>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/bits/stl_iterator.h:593:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const reverse_iterator<_IteratorL>&, const reverse_iterator<_IteratorL>&) requires requires{{std::operator==::__x->base() == std::operator==::__y->base()} -> decltype(auto) [requires std::convertible_to<<placeholder>, bool>];}' (rewritten)
593 | operator==(const reverse_iterator<_Iterator>& __x,
| ^~~~~~~~
/usr/include/c++/13/bits/stl_iterator.h:593:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::reverse_iterator<_IteratorL>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/bits/stl_iterator.h:1748:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)' (rewritten)
1748 | operator==(const move_iterator<_Iterator>& __x,
| ^~~~~~~~
/usr/include/c++/13/bits/stl_iterator.h:1748:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::move_iterator<_IteratorL>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/string_view:609:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator==(basic_string_view<_CharT, _Traits>, basic_string_view<_CharT, _Traits>)' (rewritten)
609 | operator==(basic_string_view<_CharT, _Traits> __x,
| ^~~~~~~~
/usr/include/c++/13/string_view:609:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'std::basic_string_view<_CharT, _Traits>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/bits/basic_string.h:3710:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> constexpr bool std::operator==(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)' (rewritten)
3710 | operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
| ^~~~~~~~
/usr/include/c++/13/bits/basic_string.h:3710:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/unordered_map:41,
from /usr/include/c++/13/functional:63:
/usr/include/c++/13/bits/unordered_map.h:2143:5: note: candidate: 'template<class _Key1, class _Tp1, class _Hash1, class _Pred1, class _Alloc1> bool std::operator==(const unordered_map<_Key1, _Tp1, _Hash1, _Pred1, _Alloc1>&, const unordered_map<_Key1, _Tp1, _Hash1, _Pred1, _Alloc1>&)' (rewritten)
2143 | operator==(const unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
| ^~~~~~~~
/usr/include/c++/13/bits/unordered_map.h:2143:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::unordered_map<_Key1, _Tp1, _Hash1, _Pred1, _Alloc1>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/bits/unordered_map.h:2157:5: note: candidate: 'template<class _Key1, class _Tp1, class _Hash1, class _Pred1, class _Alloc1> bool std::operator==(const unordered_multimap<_Key1, _Tp1, _Hash1, _Pred1, _Alloc1>&, const unordered_multimap<_Key1, _Tp1, _Hash1, _Pred1, _Alloc1>&)' (rewritten)
2157 | operator==(const unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
| ^~~~~~~~
/usr/include/c++/13/bits/unordered_map.h:2157:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::unordered_multimap<_Key1, _Tp1, _Hash1, _Pred1, _Alloc1>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/vector:66,
from /usr/include/c++/13/functional:64:
/usr/include/c++/13/bits/stl_vector.h:2040:5: note: candidate: 'template<class _Tp, class _Alloc> constexpr bool std::operator==(const vector<_Tp, _Alloc>&, const vector<_Tp, _Alloc>&)' (rewritten)
2040 | operator==(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
| ^~~~~~~~
/usr/include/c++/13/bits/stl_vector.h:2040:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::vector<_Tp, _Alloc>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/functional:65:
/usr/include/c++/13/array:297:5: note: candidate: 'template<class _Tp, long unsigned int _Nm> constexpr bool std::operator==(const array<_Tp, _Nm>&, const array<_Tp, _Nm>&)' (rewritten)
297 | operator==(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
| ^~~~~~~~
/usr/include/c++/13/array:297:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::array<_Tp, _Nm>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/bits/streambuf_iterator.h:234:5: note: candidate: 'template<class _CharT, class _Traits> bool std::operator==(const istreambuf_iterator<_CharT, _Traits>&, const istreambuf_iterator<_CharT, _Traits>&)' (rewritten)
234 | operator==(const istreambuf_iterator<_CharT, _Traits>& __a,
| ^~~~~~~~
/usr/include/c++/13/bits/streambuf_iterator.h:234:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::istreambuf_iterator<_CharT, _Traits>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/complex:467:5: note: candidate: 'template<class _Tp> constexpr bool std::operator==(const complex<_Tp>&, const complex<_Tp>&)' (rewritten)
467 | operator==(const complex<_Tp>& __x, const complex<_Tp>& __y)
| ^~~~~~~~
/usr/include/c++/13/complex:467:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::complex<_Tp>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/deque:66,
from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:139:
/usr/include/c++/13/bits/stl_deque.h:2290:5: note: candidate: 'template<class _Tp, class _Alloc> bool std::operator==(const deque<_Tp, _Alloc>&, const deque<_Tp, _Alloc>&)' (rewritten)
2290 | operator==(const deque<_Tp, _Alloc>& __x, const deque<_Tp, _Alloc>& __y)
| ^~~~~~~~
/usr/include/c++/13/bits/stl_deque.h:2290:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::deque<_Tp, _Alloc>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/list:65,
from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:150:
/usr/include/c++/13/bits/stl_list.h:2123:5: note: candidate: 'template<class _Tp, class _Alloc> bool std::operator==(const __cxx11::list<_Tp, _Alloc>&, const __cxx11::list<_Tp, _Alloc>&)' (rewritten)
2123 | operator==(const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y)
| ^~~~~~~~
/usr/include/c++/13/bits/stl_list.h:2123:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::__cxx11::list<_Tp, _Alloc>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/map:63,
from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:152:
/usr/include/c++/13/bits/stl_map.h:1513:5: note: candidate: 'template<class _Key, class _Tp, class _Compare, class _Alloc> bool std::operator==(const map<_Key, _Tp, _Compare, _Allocator>&, const map<_Key, _Tp, _Compare, _Allocator>&)' (rewritten)
1513 | operator==(const map<_Key, _Tp, _Compare, _Alloc>& __x,
| ^~~~~~~~
/usr/include/c++/13/bits/stl_map.h:1513:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::map<_Key, _Tp, _Compare, _Allocator>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/map:64:
/usr/include/c++/13/bits/stl_multimap.h:1134:5: note: candidate: 'template<class _Key, class _Tp, class _Compare, class _Alloc> bool std::operator==(const multimap<_Key, _Tp, _Compare, _Allocator>&, const multimap<_Key, _Tp, _Compare, _Allocator>&)' (rewritten)
1134 | operator==(const multimap<_Key, _Tp, _Compare, _Alloc>& __x,
| ^~~~~~~~
/usr/include/c++/13/bits/stl_multimap.h:1134:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::multimap<_Key, _Tp, _Compare, _Allocator>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/set:63,
from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:158:
/usr/include/c++/13/bits/stl_set.h:987:5: note: candidate: 'template<class _Key, class _Compare, class _Alloc> bool std::operator==(const set<_Key, _Compare, _Allocator>&, const set<_Key, _Compare, _Allocator>&)' (rewritten)
987 | operator==(const set<_Key, _Compare, _Alloc>& __x,
| ^~~~~~~~
/usr/include/c++/13/bits/stl_set.h:987:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::set<_Key, _Compare, _Allocator>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/set:64:
/usr/include/c++/13/bits/stl_multiset.h:973:5: note: candidate: 'template<class _Key, class _Compare, class _Alloc> bool std::operator==(const multiset<_Key, _Compare, _Allocator>&, const multiset<_Key, _Compare, _Allocator>&)' (rewritten)
973 | operator==(const multiset<_Key, _Compare, _Alloc>& __x,
| ^~~~~~~~
/usr/include/c++/13/bits/stl_multiset.h:973:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::multiset<_Key, _Compare, _Allocator>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/forward_list:42,
from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:175:
/usr/include/c++/13/bits/forward_list.tcc:393:5: note: candidate: 'template<class _Tp, class _Alloc> bool std::operator==(const forward_list<_Tp, _Alloc>&, const forward_list<_Tp, _Alloc>&)' (rewritten)
393 | operator==(const forward_list<_Tp, _Alloc>& __lx,
| ^~~~~~~~
/usr/include/c++/13/bits/forward_list.tcc:393:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::forward_list<_Tp, _Alloc>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/random:53,
from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:179:
/usr/include/c++/13/bits/random.tcc:1908:5: note: candidate: 'template<class _RealType1> bool std::operator==(const normal_distribution<_RealType>&, const normal_distribution<_RealType>&)' (rewritten)
1908 | operator==(const std::normal_distribution<_RealType>& __d1,
| ^~~~~~~~
/usr/include/c++/13/bits/random.tcc:1908:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::normal_distribution<_RealType>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/unordered_set:41,
from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:189:
/usr/include/c++/13/bits/unordered_set.h:1813:5: note: candidate: 'template<class _Value1, class _Hash1, class _Pred1, class _Alloc1> bool std::operator==(const unordered_set<_Value1, _Hash1, _Pred1, _Alloc1>&, const unordered_set<_Value1, _Hash1, _Pred1, _Alloc1>&)' (rewritten)
1813 | operator==(const unordered_set<_Value, _Hash, _Pred, _Alloc>& __x,
| ^~~~~~~~
/usr/include/c++/13/bits/unordered_set.h:1813:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::unordered_set<_Value1, _Hash1, _Pred1, _Alloc1>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/bits/unordered_set.h:1827:5: note: candidate: 'template<class _Value1, class _Hash1, class _Pred1, class _Alloc1> bool std::operator==(const unordered_multiset<_Value1, _Hash1, _Pred1, _Alloc1>&, const unordered_multiset<_Value1, _Hash1, _Pred1, _Alloc1>&)' (rewritten)
1827 | operator==(const unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __x,
| ^~~~~~~~
/usr/include/c++/13/bits/unordered_set.h:1827:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::unordered_multiset<_Value1, _Hash1, _Pred1, _Alloc1>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/system_error:449:3: note: candidate: 'bool std::operator==(const error_code&, const error_code&)' (rewritten)
449 | operator==(const error_code& __lhs, const error_code& __rhs) noexcept
| ^~~~~~~~
/usr/include/c++/13/system_error:449:32: note: no known conversion for argument 1 from 'char' to 'const std::error_code&'
449 | operator==(const error_code& __lhs, const error_code& __rhs) noexcept
| ~~~~~~~~~~~~~~~~~~^~~~~
/usr/include/c++/13/system_error:480:3: note: candidate: 'bool std::operator==(const error_condition&, const error_condition&)' (rewritten)
480 | operator==(const error_condition& __lhs,
| ^~~~~~~~
/usr/include/c++/13/system_error:480:37: note: no known conversion for argument 1 from 'char' to 'const std::error_condition&'
480 | operator==(const error_condition& __lhs,
| ~~~~~~~~~~~~~~~~~~~~~~~^~~~~
In file included from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:80:
/usr/include/c++/13/variant:1273:18: note: candidate: 'constexpr bool std::operator==(monostate, monostate)' (rewritten)
1273 | constexpr bool operator==(monostate, monostate) noexcept { return true; }
| ^~~~~~~~
/usr/include/c++/13/variant:1273:29: note: no known conversion for argument 1 from 'char' to 'std::monostate'
1273 | constexpr bool operator==(monostate, monostate) noexcept { return true; }
| ^~~~~~~~~
In file included from /usr/include/c++/13/stop_token:37,
from /usr/include/c++/13/condition_variable:49,
from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:174:
/usr/include/c++/13/bits/std_thread.h:324:3: note: candidate: 'bool std::operator==(thread::id, thread::id)' (rewritten)
324 | operator==(thread::id __x, thread::id __y) noexcept
| ^~~~~~~~
/usr/include/c++/13/bits/std_thread.h:324:25: note: no known conversion for argument 1 from 'char' to 'std::thread::id'
324 | operator==(thread::id __x, thread::id __y) noexcept
| ~~~~~~~~~~~^~~
/usr/include/c++/13/bits/allocator.h:216:7: note: candidate: 'constexpr bool std::operator==(const allocator<char>&, const allocator<char>&)' (rewritten)
216 | operator==(const allocator&, const allocator&) _GLIBCXX_NOTHROW
| ^~~~~~~~
/usr/include/c++/13/bits/allocator.h:216:18: note: no known conversion for argument 1 from 'char' to 'const std::allocator<char>&'
216 | operator==(const allocator&, const allocator&) _GLIBCXX_NOTHROW
| ^~~~~~~~~~~~~~~~
/usr/include/c++/13/bits/stl_iterator.h:542:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator!=(const reverse_iterator<_IteratorL>&, const reverse_iterator<_IteratorR>&) requires requires{{std::operator!=::__x->base() != std::operator!=::__y->base()} -> decltype(auto) [requires std::convertible_to<<placeholder>, bool>];}'
542 | operator!=(const reverse_iterator<_IteratorL>& __x,
| ^~~~~~~~
/usr/include/c++/13/bits/stl_iterator.h:542:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::reverse_iterator<_IteratorL>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/bits/char_traits.h:42,
from /usr/include/c++/13/string:42:
/usr/include/c++/13/bits/postypes.h:197:5: note: candidate: 'template<class _StateT> bool std::operator!=(const fpos<_StateT>&, const fpos<_StateT>&)'
197 | operator!=(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
| ^~~~~~~~
/usr/include/c++/13/bits/postypes.h:197:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::fpos<_StateT>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/optional:1245:5: note: candidate: 'template<class _Tp, class _Up> constexpr std::__optional_ne_t<_Tp, _Up> std::operator!=(const optional<_Tp>&, const optional<_Up>&)'
1245 | operator!=(const optional<_Tp>& __lhs, const optional<_Up>& __rhs)
| ^~~~~~~~
/usr/include/c++/13/optional:1245:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::optional<_Tp>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/optional:1376:5: note: candidate: 'template<class _Tp, class _Up> constexpr std::__optional_ne_t<_Tp, _Up> std::operator!=(const optional<_Tp>&, const _Up&)'
1376 | operator!=(const optional<_Tp>& __lhs, const _Up& __rhs)
| ^~~~~~~~
/usr/include/c++/13/optional:1376:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::optional<_Tp>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/optional:1382:5: note: candidate: 'template<class _Tp, class _Up> constexpr std::__optional_ne_t<_Up, _Tp> std::operator!=(const _Up&, const optional<_Tp>&)'
1382 | operator!=(const _Up& __lhs, const optional<_Tp>& __rhs)
| ^~~~~~~~
/usr/include/c++/13/optional:1382:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::optional<_Tp>'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/variant:1267:3: note: candidate: 'template<class ... _Types> constexpr bool std::operator!=(const variant<_Types ...>&, const variant<_Types ...>&)'
1267 | _VARIANT_RELATION_FUNCTION_TEMPLATE(!=, not_equal)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/variant:1267:3: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::variant<_Types ...>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/queue:66,
from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:157:
/usr/include/c++/13/bits/stl_queue.h:406:5: note: candidate: 'template<class _Tp, class _Seq> bool std::operator!=(const queue<_Tp, _Seq>&, const queue<_Tp, _Seq>&)'
406 | operator!=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
| ^~~~~~~~
/usr/include/c++/13/bits/stl_queue.h:406:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::queue<_Tp, _Seq>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/stack:63,
from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:160:
/usr/include/c++/13/bits/stl_stack.h:382:5: note: candidate: 'template<class _Tp, class _Seq> bool std::operator!=(const stack<_Tp, _Seq>&, const stack<_Tp, _Seq>&)'
382 | operator!=(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)
| ^~~~~~~~
/usr/include/c++/13/bits/stl_stack.h:382:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::stack<_Tp, _Seq>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
In file included from /usr/include/c++/13/valarray:605,
from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:166:
/usr/include/c++/13/bits/valarray_after.h:418:5: note: candidate: 'template<class _Dom1, class _Dom2> std::_Expr<std::__detail::_BinClos<std::__not_equal_to, std::_Expr, std::_Expr, _Dom1, _Dom2>, typename std::__fun<std::__not_equal_to, typename _Dom1::value_type>::result_type> std::operator!=(const _Expr<_Dom1, typename _Dom1::value_type>&, const _Expr<_Dom2, typename _Dom2::value_type>&)'
418 | _DEFINE_EXPR_BINARY_OPERATOR(!=, struct std::__not_equal_to)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/bits/valarray_after.h:418:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/bits/valarray_after.h:418:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__not_equal_to, std::_Expr, std::_Constant, _Dom, typename _Dom::value_type>, typename std::__fun<std::__not_equal_to, typename _Dom1::value_type>::result_type> std::operator!=(const _Expr<_Dom1, typename _Dom1::value_type>&, const typename _Dom::value_type&)'
418 | _DEFINE_EXPR_BINARY_OPERATOR(!=, struct std::__not_equal_to)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/bits/valarray_after.h:418:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/bits/valarray_after.h:418:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__not_equal_to, std::_Constant, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__not_equal_to, typename _Dom1::value_type>::result_type> std::operator!=(const typename _Dom::value_type&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
418 | _DEFINE_EXPR_BINARY_OPERATOR(!=, struct std::__not_equal_to)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/bits/valarray_after.h:418:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/bits/valarray_after.h:418:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__not_equal_to, std::_Expr, std::_ValArray, _Dom, typename _Dom::value_type>, typename std::__fun<std::__not_equal_to, typename _Dom1::value_type>::result_type> std::operator!=(const _Expr<_Dom1, typename _Dom1::value_type>&, const valarray<typename _Dom::value_type>&)'
418 | _DEFINE_EXPR_BINARY_OPERATOR(!=, struct std::__not_equal_to)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/bits/valarray_after.h:418:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/bits/valarray_after.h:418:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__not_equal_to, std::_ValArray, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__not_equal_to, typename _Dom1::value_type>::result_type> std::operator!=(const valarray<typename _Dom::value_type>&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
418 | _DEFINE_EXPR_BINARY_OPERATOR(!=, struct std::__not_equal_to)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/bits/valarray_after.h:418:5: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/valarray:1209:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__not_equal_to, std::_ValArray, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__not_equal_to, _Tp>::result_type> std::operator!=(const valarray<_Tp>&, const valarray<_Tp>&)'
1209 | _DEFINE_BINARY_OPERATOR(!=, __not_equal_to)
| ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/valarray:1209:1: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::valarray<_Tp>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/valarray:1209:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__not_equal_to, std::_ValArray, std::_Constant, _Tp, _Tp>, typename std::__fun<std::__not_equal_to, _Tp>::result_type> std::operator!=(const valarray<_Tp>&, const typename valarray<_Tp>::value_type&)'
1209 | _DEFINE_BINARY_OPERATOR(!=, __not_equal_to)
| ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/valarray:1209:1: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: mismatched types 'const std::valarray<_Tp>' and 'char'
20 | if(c != first) s1 += c;
| ^~~~~
/usr/include/c++/13/valarray:1209:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__not_equal_to, std::_Constant, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__not_equal_to, _Tp>::result_type> std::operator!=(const typename valarray<_Tp>::value_type&, const valarray<_Tp>&)'
1209 | _DEFINE_BINARY_OPERATOR(!=, __not_equal_to)
| ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/valarray:1209:1: note: template argument deduction/substitution failed:
combo.cpp:20:17: note: 'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::valarray<_Tp>'
20 | if(c != first) s1 += c;
| ^~~~~