Compilare: main.cpp: In function 'void solve1(std::vector<std::vector<int> >&)': main.cpp:59:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare] 59 | for (int i = 0; i < mat.size(); i++) { | ~~^~~~~~~~~~~~ main.cpp:60:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 60 | for (int j = 0; j < mat[i].size(); j++) { | ~~^~~~~~~~~~~~~~~ main.cpp:54:9: warning: unused variable 'lineDirection' [-Wunused-variable] 54 | int lineDirection[] = {0, 0, 1, -1}; | ^~~~~~~~~~~~~ main.cpp:55:9: warning: unused variable 'columnDirection' [-Wunused-variable] 55 | int columnDirection[] = {1, -1, 0, 0}; | ^~~~~~~~~~~~~~~ main.cpp: In function 'bool checkMatrix(const std::vector<std::vector<int> >&, int)': main.cpp:77:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare] 77 | for (int i = 0; i < mat.size(); i++) { | ~~^~~~~~~~~~~~ main.cpp:78:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 78 | for (int j = 0; j < mat[i].size(); j++) { | ~~^~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:103:32: warning: comparison of integer expressions of different signedness: 'unsigned int' and 'int' [-Wsign-compare] 103 | for (unsigned int i = 0; i < lines; i++) { | ~~^~~~~~~ main.cpp:104:36: warning: comparison of integer expressions of different signedness: 'unsigned int' and 'int' [-Wsign-compare] 104 | for (unsigned int j = 0; j < columns; j++) { | ~~^~~~~~~~~ main.cpp:100:9: warning: variable 'maxFrequencyNumber' set but not used [-Wunused-but-set-variable] 100 | int maxFrequencyNumber = -(1<< 20); | ^~~~~~~~~~~~~~~~~~