islands.cpp: In function 'void dfs(int, int, int)':
islands.cpp:17:14: error: cannot decompose non-array non-class type 'int'
17 | for(auto [x, i] : g[v]){
| ^~~~~~
islands.cpp: In function 'std::variant<bool, std::vector<int, std::allocator<int> > > find_journey(int, int, std::vector<int>, std::vector<int>)':
islands.cpp:32:26: error: no matching function for call to 'std::vector<int>::push_back(<brace-enclosed initializer list>)'
32 | g[U[i]].push_back({V[i], i/2});
| ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~
In file included from /usr/include/c++/11/vector:67,
from islands.h:2,
from islands.cpp:1:
/usr/include/c++/11/bits/stl_vector.h:1187:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(const value_type&) [with _Tp = int; _Alloc = std::allocator<int>; std::vector<_Tp, _Alloc>::value_type = int]'
1187 | push_back(const value_type& __x)
| ^~~~~~~~~
/usr/include/c++/11/bits/stl_vector.h:1187:35: note: no known conversion for argument 1 from '<brace-enclosed initializer list>' to 'const value_type&' {aka 'const int&'}
1187 | push_back(const value_type& __x)
| ~~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/11/bits/stl_vector.h:1203:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(std::vector<_Tp, _Alloc>::value_type&&) [with _Tp = int; _Alloc = std::allocator<int>; std::vector<_Tp, _Alloc>::value_type = int]'
1203 | push_back(value_type&& __x)
| ^~~~~~~~~
/usr/include/c++/11/bits/stl_vector.h:1203:30: note: no known conversion for argument 1 from '<brace-enclosed initializer list>' to 'std::vector<int>::value_type&&' {aka 'int&&'}
1203 | push_back(value_type&& __x)
| ~~~~~~~~~~~~~^~~