roads.cpp: In function 'void dfs(int, int, int, std::vector<std::vector<std::pair<int, int> > >&, std::vector<std::vector<long long int> >&)':
roads.cpp:14:13: warning: unused variable 'cost' [-Wunused-variable]
14 | int cost = edge.second;
| ^~~~
/usr/bin/ld: /tmp/ccWbl2oq.o: in function `main':
grader.cpp:(.text.startup+0x277): undefined reference to `minimum_closure_costs(int, std::vector<int, std::allocator<int> >, std::vector<int, std::allocator<int> >, std::vector<int, std::allocator<int> >)'
collect2: error: ld returned 1 exit status