books.cpp: In function 'void solve(int, int, long long int, int)':
books.cpp:41:4: error: 'vector' was not declared in this scope
41 | vector < int > rt;
| ^~~~~~
books.cpp:41:4: note: suggested alternatives:
In file included from /usr/include/c++/10/vector:67,
from books.h:4,
from books.cpp:1:
/usr/include/c++/10/bits/stl_vector.h:389:11: note: 'std::vector'
389 | class vector : protected _Vector_base<_Tp, _Alloc>
| ^~~~~~
In file included from books.h:4,
from books.cpp:1:
/usr/include/c++/10/vector:86:13: note: 'std::pmr::vector'
86 | using vector = std::vector<_Tp, polymorphic_allocator<_Tp>>;
| ^~~~~~
books.cpp:41:13: error: expected primary-expression before 'int'
41 | vector < int > rt;
| ^~~
books.cpp:45:5: error: 'rt' was not declared in this scope; did you mean 'r'?
45 | rt.push_back(j);
| ^~
| r
books.cpp:50:5: error: 'rt' was not declared in this scope; did you mean 'r'?
50 | rt.push_back(j);
| ^~
| r
books.cpp:53:11: error: 'rt' was not declared in this scope; did you mean 'r'?
53 | answer(rt);
| ^~
| r