Compilare: main.cpp: In function 'void bfs_col(const std::vector<std::vector<int> >&, std::vector<std::vector<bool> >&, int, int, int)': main.cpp:34:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare] 34 | if (ni < 0 || ni >= island.size() || nj < 0 || nj >= island[0].size()) | ~~~^~~~~~~~~~~~~~~~ main.cpp:34:57: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 34 | if (ni < 0 || ni >= island.size() || nj < 0 || nj >= island[0].size()) | ~~~^~~~~~~~~~~~~~~~~~~