Language: C++

#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef pair<int, int> pii;
const int INF = (int) 1e9;
#define MP make_pair

template <typename T> class dijkstra {
public:

    struct edge {
        T to;
        ll cost;
    };

    typedef pair<ll, T> P;
    unordered_map<T, vector<edge> > E;
   unordered_map<T, ll> d;

    void calc(T s) {
        priority_queue <P, vector<P>, greater<P> > que; 
        que.emplace(0LL, s);
        while (!que.empty()) {
            P p = que.top();
            que.pop();
            T v = p.second;
            if (d[v] == 0 && v != s) d[v] = INF;
            if (d[v] < p.first) continue;

            for (auto& e : E[v]) {
                if (d[e.to] == 0 && e.to != s) d[e.to] = INF;
                if (d[e.to] > d[v] + e.cost) {
                    d[e.to] = d[v] + e.cost;
                    que.emplace(d[e.to], e.to);
                }
            }
        }
    }
};

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    int n, m;
    cin >> n >> m;

    dijkstra<pii> ds;

    for (int i = 0; i < m; i++) {
        int p, q, c;
        cin >> p >> q >> c;
        ds.E[MP(p, c)].push_back({MP(q, c), 0});
        ds.E[MP(q, c)].push_back({MP(p, c), 0});
        ds.E[MP(p, c)].push_back({MP(p, -1), 0});
        ds.E[MP(q, c)].push_back({MP(q, -1), 0});
        ds.E[MP(p, -1)].push_back({MP(p, c), 1});
        ds.E[MP(q, -1)].push_back({MP(q, c), 1});
    }

    ds.calc(MP(1, -1));
    cout << (ds.d[MP(n, -1)] == 0 ? -1 : ds.d[MP(n, -1)]) << endl;
    return 0;
}



Compiler output:
a.cc: In function 'int main()':
a.cc:48:19: error: use of deleted function 'dijkstra<std::pair<int, int> >::dijkstra()'
   48 |     dijkstra<pii> ds;
      |                   ^~
a.cc:8:29: note: 'dijkstra<std::pair<int, int> >::dijkstra()' is implicitly deleted because the default definition would be ill-formed:
    8 | template <typename T> class dijkstra {
      |                             ^~~~~~~~
a.cc: At global scope:
a.cc:8:29: error: use of deleted function 'std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_map() [with _Key = std::pair<int, int>; _Tp = std::vector<dijkstra<std::pair<int, int> >::edge, std::allocator<dijkstra<std::pair<int, int> >::edge> >; _Hash = std::hash<std::pair<int, int> >; _Pred = std::equal_to<std::pair<int, int> >; _Alloc = std::allocator<std::pair<const std::pair<int, int>, std::vector<dijkstra<std::pair<int, int> >::edge, std::allocator<dijkstra<std::pair<int, int> >::edge> > > >]'
In file included from /usr/include/c++/14/unordered_map:41,
                 from /usr/include/c++/14/functional:63,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53,
                 from a.cc:1:
/usr/include/c++/14/bits/unordered_map.h:148:7: note: 'std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_map() [with _Key = std::pair<int, int>; _Tp = std::vector<dijkstra<std::pair<int, int> >::edge, std::allocator<dijkstra<std::pair<int, int> >::edge> >; _Hash = std::hash<std::pair<int, int> >; _Pred = std::equal_to<std::pair<int, int> >; _Alloc = std::allocator<std::pair<const std::pair<int, int>, std::vector<dijkstra<std::pair<int, int> >::edge, std::allocator<dijkstra<std::pair<int, int> >::edge> > > >]' is implicitly deleted because the default definition would be ill-formed:
  148 |       unordered_map() = default;
      |       ^~~~~~~~~~~~~
/usr/include/c++/14/bits/unordered_map.h:148:7: error: use of deleted function 'std::_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::_Hashtable() [with _Key = std::pair<int, int>; _Value = std::pair<const std::pair<int, int>, std::vector<dijkstra<std::pair<int, int> >::edge, std::allocator<dijkstra<std::pair<int, int> >::edge> > >; _Alloc = std::allocator<std::pair<const std::pair<int, int>, std::vector<dijkstra<std::pair<int, int> >::edge, std::allocator<dijkstra<std::pair<int, int> >::edge> > > >; _ExtractKey = std::__detail::_Select1st; _Equal = std::equal_to<std::pair<int, int> >; _Hash = std::hash<std::pair<int, int> >; _RangeHash = std::__detail::_Mod_range_hashing; _Unused = std::__detail::_Default_ranged_hash; _RehashPolicy = std::__detail::_Prime_rehash_policy; _Traits = std::__detail::_Hashtable_traits<true, false, true>]'
In file included from /usr/include/c++/14/bits/unordered_map.h:33:
/usr/include/c++/14/bits/hashtable.h:539:7: note: 'std::_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::_Hashtable() [with _Key = std::pair<int, int>; _Value = std::pair<const std::pair<int, int>, std::vector<dijkstra<std::pair<int, int> >::edge, std::allocator<dijkstra<std::pair<int, int> >::edge> > >; _Alloc = std::allocator<std::pair<const std::pair<int, int>, std::vector<dijkstra<std::pair<int, int> >::edge, std::allocator<dijkstra<std::pair<int, int> >::edge> > > >; _ExtractKey = std::__detail::_Select1st; _Equal = std::equal_to<std::pair<int, int> >; _Hash = std::hash<std::pair<int, int> >; _RangeHash = std::__detail::_Mod_range_hashing; _Unused = std::__detail::_Default_ranged_hash; _RehashPolicy = std::__detail::_Prime_rehash_policy; _Traits = std::__detail::_Hashtable_traits<true, false, true>]' is implicitly deleted because the default definition would be ill-formed:
  539 |       _Hashtable() = default;
      |       ^~~~~~~~~~
/usr/include/c++/14/bits/hashtable.h:539:7: error: use of deleted function 'std::__detail::_Hashtable_base<_Key, _Value, _ExtractKey, _Equal, _Hash, _RangeHash, _Unused, _Traits>::_Hashtable_base() [with _Key = std::pair<int, int>; _Value = std::pair<const std::pair<int, int>, std::vector<dijkstra<std::pair<int, int> >::edge, std::allocator<dijkstra<std::pair<int, int> >::edge> > >; _ExtractKey = std::__detail::_Select1st; _Equal = std::equal_to<std::pair<int, int> >; _Hash = std::hash<std::pair<int, int> >; _RangeHash = std::__detail::_Mod_range_hashing; _Unused = std::__detail::_Default_ranged_hash; _Traits = std::__detail::_Hashtable_traits<true, false, true>]'
In file included from /usr/include/c++/14/bits/hashtable.h:35:
/usr/include/c++/14/bits/hashtable_policy.h:1731:7: note: 'std::__detail::_Hashtable_base<_Key, _Value, _ExtractKey, _Equal, _Hash, _RangeHash, _Unused, _Traits>::_Hashtable_base() [with _Key = std::pair<int, int>; _Value = std::pair<const std::pair<int, int>, std::vector<dijkstra<std::pair<int, int> >::edge, std::allocator<dijkstra<std::pair<int, int> >::edge> > >; _ExtractKey = std::__detail::_Select1st; _Equal = std::equal_to<std::pair<int, int> >; _Hash = std::hash<std::pair<int, int> >; _RangeHash = std::__detail::_Mod_range_hashing; _Unused = std::__detail::_Default_ranged_hash; _Traits = std::__detail::_Hashtable_traits<true, false, true>]' is implicitly deleted because the default definition would be ill-formed:
 1731 |       _Hashtable_base() = default;
      |       ^~~~~~~~~~~~~~~
/usr/include/c++/14/bits/hashtable_policy.h:1731:7: error: use of deleted function 'std::__detail::_Hash_code_base<_Key, _Value, _ExtractKey, _Hash, _RangeHash, _Unused, __cache_hash_code>::_Hash_code_base() [with _Key = std::pair<int, int>; _Value = std::pair<const std::pair<int, int>, std::vector<dijkstra<std::pair<int, int> >::edge, std::allocator<dijkstra<std::pair<int, int> >::edge> > >; _ExtractKey = std::__detail::_Select1st; _Hash = std::hash<std::pair<int, int> >; _RangeHash = std::__detail::_Mod_range_hashing; _Unused = std::__detail::_Default_ranged_hash; bool __cache_hash_code = true]'
/usr/include/c++/14/bits/hashtable_policy.h: In instantiation of 'std::__detail::_Hashtable_ebo_helper<_Nm, _Tp, true>::_Hashtable_ebo_helper() [with int _Nm = 1; _Tp = std::hash<std::pair<int, int> >]':
/usr/include/c++/14/bits/hashtable_policy.h:1328:7:   required from here
 1328 |       _Hash_code_base() = default;
      |       ^~~~~~~~~~~~~~~
/usr/include/c++/14/bits/hashtable_policy.h:1245:49: error: use of deleted function 'std::hash<std::pair<int, int> >::hash()'
 1245 |       _Hashtable_ebo_helper() noexcept(noexcept(_Tp())) : _Tp() { }
      |                                                 ^~~~~
In file included from /usr/include/c++/14/string_view:50,
                 from /usr/include/c++/14/bits/basic_string.h:47,
                 from /usr/include/c++/14/string:54,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/usr/include/c++/14/bits/functional_hash.h:102:12: note: 'std::hash<std::pair<int, int> >::hash()' is implicitly deleted because the default definition would be ill-formed:
  102 |     struct hash : __hash_enum<_Tp>
      |            ^~~~
/usr/include/c++/14/bits/functional_hash.h:102:12: error: no matching function for call to 'std::__hash_enum<std::pair<int, int>, false>::__hash_enum()'
/usr/include/c++/14/bits/functional_hash.h:83:7: note: candidate: 'std::__hash_enum<_Tp, <anonymous> >::__hash_enum(std::__hash_enum<_Tp, <anonymous> >&&) [with _Tp = std::pair<int, int>; bool <anonymous> = false]'
   83 |       __hash_enum(__hash_enum&&);
      |       ^~~~~~~~~~~
/usr/include/c++/14/bits/functional_hash.h:83:7: note:   candidate expects 1 argument, 0 provided
/usr/include/c++/14/bits/functional_hash.h:102:12: error: 'std::__hash_enum<_Tp, <anonymous> >::~__hash_enum() [with _Tp = std::pair<int, int>; bool <anonymous> = false]' is private within this context
  102 |     struct hash : __hash_enum<_Tp>
      |            ^~~~
/usr/include/c++/14/bits/functional_hash.h:84:7: note: declared private here
   84 |       ~__hash_enum();
      |       ^
/usr/include/c++/14/bits/hashtable_policy.h:1245:49: note: use '-fdiagnostics-all-candidates' to display considered candidates
 1245 |       _Hashtable_ebo_helper() noexcept(noexcept(_Tp())) : _Tp() { }
      |                                                 ^~~~~
/usr/include/c++/14/bits/hashtable_policy.h:1328:7: note: 'std::__detail::_Hash_code_base<_Key, _Value, _ExtractKey, _Hash, _RangeHash, _Unused, __cache_hash_code>::_Hash_code_base() [with _Key = std::pair<int, int>; _Value = std::pair<const std::pair<int, int>, std::vector<dijkstra<std::pair<int, int> >::edge, std::allocator<dijkstra<std::pair<int, int> >::edge> > >; _ExtractKey = std::__detail::_Select1st; _Hash = std::hash<std::pair<int, int> >; _RangeHash = std::__detail::_Mod_range_hashing; _Unused = std::__detail::_Default_ranged_hash; bool __cache_hash_code = true]' is implicitly deleted because the default definition would be ill-formed:
 1328 |       _Hash_code_base() = default;
      |       ^~~~~~~~~~~~~~~
/usr/include/c++/14/bits/hashtable_policy.h:1328:7: error: use of deleted function 'std::__detail::_Hashtable_ebo_helper<1, std::hash<std::pair<int, int> >, true>::~_Hashtable_ebo_helper()'
/usr/include/c++/14/bits/hashtable_policy.h:1242:12: note: 'std::__detail::_Hashtable_ebo_helper<1, std::hash<std::pair<int, int> >, true>::~_Hashtable_ebo_helper()' is implicitly deleted because the default definition would be ill-formed:
 1242 |     struct _Hashtable_ebo_helper<_Nm, _Tp, true>
      |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/hashtable_policy.h:1242:12: error: use of deleted function 'std::hash<std::pair<int, int> >::~hash()'
/usr/include/c++/14/bits/functional_hash.h:102:12: note: 'std::hash<std::pair<int, int> >::~hash()' is implicitly deleted because the default definition would be ill-formed:
  102 |     struct hash : __hash_enum<_Tp>
      |            ^~~~
/usr/include/c++/14/bits/functional_hash.h:102:12: error: 'std::__hash_enum<_Tp, <anonymous> >::~__hash_enum() [with _Tp = std::pair<int, int>; bool <anonymous> = false]' is private within this context
/usr/include/c++/14/bits/functional_hash.h:84:7: note: declared private here