Compilare: main.cpp: In function 'bool valid()': main.cpp:11:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 11 | for (int i = 0; i < perm.size() - 1; i++) | ~~^~~~~~~~~~~~~~~~~ main.cpp: In function 'void print()': main.cpp:18:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 18 | for (int i = 0; i < perm.size(); i++) | ~~^~~~~~~~~~~~~ main.cpp: In function 'void backtracking()': main.cpp:27:23: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare] 27 | if (perm.size() == n) | ~~~~~~~~~~~~^~~~