mars.cpp: In function 'void dfs(int, int, int)':
mars.cpp:11:8: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
11 | if(i < m.size() - 1) dfs(i+1, j, z);
| ~~^~~~~~~~~~~~~~
mars.cpp:12:8: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
12 | if(j < m.size() - 1) dfs(i, j+1, z);
| ~~^~~~~~~~~~~~~~
mars.cpp: In function 'std::vector<std::vector<int> > decode(std::string, int)':
mars.cpp:25:1: warning: no return statement in function returning non-void [-Wreturn-type]
25 | }
| ^
mars.cpp: In function 'std::string encode(std::vector<std::vector<int> >)':
mars.cpp:28:1: warning: no return statement in function returning non-void [-Wreturn-type]
28 | }
| ^
mars.cpp: In function 'std::string process(std::vector<std::vector<std::__cxx11::basic_string<char> > >, int, int, int, int)':
mars.cpp:63:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
63 | for(int r = 0; r < grid.size(); r ++){
| ~~^~~~~~~~~~~~~
mars.cpp:64:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
64 | for(int c = 0; c < grid[r].size(); c ++){
| ~~^~~~~~~~~~~~~~~~
mars.cpp:90:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
90 | for(int r = 0; r < grid.size(); r ++){
| ~~^~~~~~~~~~~~~
mars.cpp:91:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
91 | for(int c = 0; c < grid[r].size(); c ++){
| ~~^~~~~~~~~~~~~~~~
mars.cpp:95:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
95 | for(int r = 0; r < grid01.size(); r ++){
| ~~^~~~~~~~~~~~~~~
mars.cpp:96:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
96 | for(int c = 0; c < grid01[r].size(); c ++){
| ~~^~~~~~~~~~~~~~~~~~
mars.cpp:100:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
100 | for(int r = 0; r < grid10.size(); r ++){
| ~~^~~~~~~~~~~~~~~
mars.cpp:101:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
101 | for(int c = 0; c < grid10[r].size(); c ++){
| ~~^~~~~~~~~~~~~~~~~~
mars.cpp:105:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
105 | for(int r = 0; r < grid11.size(); r ++){
| ~~^~~~~~~~~~~~~~~
mars.cpp:106:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
106 | for(int c = 0; c < grid11[r].size(); c ++){
| ~~^~~~~~~~~~~~~~~~~~
mars.cpp:113:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
113 | for(int r = 0; r < matrix.size(); r ++){
| ~~^~~~~~~~~~~~~~~
mars.cpp:114:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
114 | for(int c = 0; c < matrix[r].size(); c ++){
| ~~^~~~~~~~~~~~~~~~~~
mars.cpp:124:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
124 | for(int i = 0; i < v.size(); i ++){
| ~~^~~~~~~~~~
mars.cpp:125:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
125 | for(int j = 0; j < v[i].size(); j ++){
| ~~^~~~~~~~~~~~~