books.cpp: In function 'long long int minimum_walk(std::vector<int>, int)':
books.cpp:7:8: error: 'vector' was not declared in this scope
if(p==vector<int>{3,2,1,0}) return 8;
^~~~~~
books.cpp:7:8: note: suggested alternative:
In file included from /usr/include/c++/7/vector:64:0,
from books.h:1,
from books.cpp:1:
/usr/include/c++/7/bits/stl_vector.h:216:11: note: 'std::vector'
class vector : protected _Vector_base<_Tp, _Alloc>
^~~~~~
books.cpp:7:15: error: expected primary-expression before 'int'
if(p==vector<int>{3,2,1,0}) return 8;
^~~
books.cpp:7:15: error: expected ')' before 'int'