books.cpp: In function 'bool valid(std::vector<int>)':
books.cpp:14:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
14 | for (int i = 1; i < v.size(); i++){
| ~~^~~~~~~~~~
books.cpp: In function 'long long int minimum_walk(std::vector<int>, int)':
books.cpp:28:9: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
28 | if (i < v.size()-1) bfs.push_back(make_pair(make_pair(i+1, t+1), make_pair(b, v)));
| ~~^~~~~~~~~~~~
books.cpp:33:10: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
33 | if (i < v.size()-1) bfs.push_back(make_pair(make_pair(i+1, t+1), make_pair(-1, nv)));
| ~~^~~~~~~~~~~~
books.cpp:38:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
38 | if (i < v.size()-1) bfs.push_back(make_pair(make_pair(i+1, t+1), make_pair(temp, nv)));
| ~~^~~~~~~~~~~~
books.cpp:42:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
42 | if (i < v.size()-1) bfs.push_back(make_pair(make_pair(i+1, t+1), make_pair(temp, nv)));
| ~~^~~~~~~~~~~~
books.cpp:23:57: warning: control reaches end of non-void function [-Wreturn-type]
23 | deque<pair<pair<int, int>, pair<int, vector<int> > > > bfs; bfs.push_back(make_pair(make_pair(0, 0), make_pair(-1, p)));
| ^~~