citymapping.cpp: In function 'void find_roads(int, int, int*, int*, int*)':
citymapping.cpp:25:8: warning: statement has no effect [-Wunused-value]
25 | p[i] == i;
| ~~~~~^~~~
citymapping.cpp:31:9: error: '_merge' was not declared in this scope
31 | if (_merge(i, j)) {
| ^~~~~~
citymapping.cpp:46:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, std::pair<int, int> > >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
46 | for (int i = 0; i < e.size(); i++) {
| ~~^~~~~~~~~~
citymapping.cpp:52:22: error: expected ';' before '}' token
52 | W[xx] = e[i].first
| ^
| ;
53 | }
| ~