Submission #438661

#	Time	Username	Problem	Language	Result	Execution time	Memory
438661		raid	Rack (eJOI19_rack)	C++17	100 / 100	13 ms	7992 KiB

rack

#include <iostream>
#include <vector>

using namespace std;

const int MOD = 1e9 + 7;
const int MAXN = 1e6 + 1;

vector<int> db;
int pmod[MAXN];

int main() {
  int n;
  long long k;

  cin >> n >> k;
  --k;
  while ( k ) {
	db.push_back( k & 1 );
	k >>= 1;
  }
  while ( db.size() != n ) {
    db.push_back( 0 );
  }
  pmod[0] = 1;
  for ( int i = 1; i <= n; ++i ) {
	pmod[i] = (pmod[i - 1] * 2) % MOD;
  }
  long long res = 0;
  for ( int i = 0; i < n; ++i ) {
	if ( db[i] ) {
 	  res = (res + pmod[n - i - 1]) % MOD;
    }
  }
  cout << (res + 1) % MOD;
  return 0;
}

Compilation message (stderr)

rack.cpp: In function 'int main()':
rack.cpp:22:21: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   22 |   while ( db.size() != n ) {
      |           ~~~~~~~~~~^~~~

• Subtask 1: 20 / 20
• Subtask 2: 20 / 20
• Subtask 3: 60 / 60