Submission #1220598

#	Time	Username	Problem	Language	Result	Execution time	Memory
1220598		durdona	Rack (eJOI19_rack)	C++20	Compilation error	0 ms	0 KiB

rack

#include <bits/stdc++.h>
using ull = unsigned long long;
const int mod = 1e9 + 7;
int power(int a, int b){
  if(b == 0) return 1;
  if(b == 1) return a % mod;
  if(b % 2 == 0){
    int y = power(a, b / 2);
    return y * y % mod;
  }else return power(a, b - 1) * a % mod;
}

void solve()
{
  int n, k; cin >> n >> k;
  auto rec = [&](auto&& rec, int i, int j) -> int{
    if(i == 1) return 1;
    if(j % 2) return rec(rec, i - 1, j / 2 + 1);
    else return (rec(rec, i - 1, j / 2) + power(2, i - 1)) % mod;
  };

  cout << rec(rec, n, k);

}
 
signed main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int t = 1; //cin >> t;
  while(t--){
    solve();
    cout << endl;
  }
  return 0;
}

Compilation message (stderr)

rack.cpp: In function 'void solve()':
rack.cpp:15:13: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
   15 |   int n, k; cin >> n >> k;
      |             ^~~
      |             std::cin
In file included from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:75,
                 from rack.cpp:1:
/usr/include/c++/11/iostream:60:18: note: 'std::cin' declared here
   60 |   extern istream cin;           /// Linked to standard input
      |                  ^~~
rack.cpp:22:3: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   22 |   cout << rec(rec, n, k);
      |   ^~~~
      |   std::cout
In file included from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:75,
                 from rack.cpp:1:
/usr/include/c++/11/iostream:61:18: note: 'std::cout' declared here
   61 |   extern ostream cout;          /// Linked to standard output
      |                  ^~~~
rack.cpp: In function 'int main()':
rack.cpp:27:3: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
   27 |   cin.tie(nullptr)->sync_with_stdio(false);
      |   ^~~
      |   std::cin
In file included from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:75,
                 from rack.cpp:1:
/usr/include/c++/11/iostream:60:18: note: 'std::cin' declared here
   60 |   extern istream cin;           /// Linked to standard input
      |                  ^~~
rack.cpp:31:5: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   31 |     cout << endl;
      |     ^~~~
      |     std::cout
In file included from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:75,
                 from rack.cpp:1:
/usr/include/c++/11/iostream:61:18: note: 'std::cout' declared here
   61 |   extern ostream cout;          /// Linked to standard output
      |                  ^~~~
rack.cpp:31:13: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   31 |     cout << endl;
      |             ^~~~
      |             std::endl
In file included from /usr/include/c++/11/istream:39,
                 from /usr/include/c++/11/sstream:38,
                 from /usr/include/c++/11/complex:45,
                 from /usr/include/c++/11/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:54,
                 from rack.cpp:1:
/usr/include/c++/11/ostream:684:5: note: 'std::endl' declared here
  684 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~