Submission #282392

#	Time	Username	Problem	Language	Result	Execution time	Memory
282392		lani1akea	Rack (eJOI19_rack)	C++17	100 / 100	2 ms	512 KiB

rack

#include <bits/stdc++.h>

#define F first
#define S second
#define ll long long
#define pb push_back
#define endl '\n'

using namespace std;

const int MOD = 1e9+7;
ll e(ll a, ll b) {
  if (!b) return 1;
  ll res = e(a, b / 2);
  if (b % 2)
  return (res * res * a) % MOD;
  return (res * res) % MOD;
}

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0); cout.tie(0);
  ll n, k;
  cin >> n >> k;
  ll ans = 1;
  for (int i = n - 1; i >= 0; --i) {
    if (!(k % 2)) {
      ans = (ans + e(2, i)) % MOD;
    }
    k = (k + 1) / 2;
  }
  cout << ans << endl;
}

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