Submission #256008

#	Time	Username	Problem	Language	Result	Execution time	Memory
256008		jdh	Rack (eJOI19_rack)	C++17	100 / 100	9 ms	7936 KiB

rack

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll mod = 1e9+7;
int main(){
  ios::sync_with_stdio(0);
  cin.tie(0);
  ll n,k;
  cin >> n >> k;
  vector<ll> pow2(n);
  pow2[0] = 1;
  for(int i = 1; i < n; ++i) pow2[i] = (2*pow2[i-1])%mod;
  ll ans = 1;
  int idx = n-1;
  while(true){
    if(k%2 == 0) ans = (ans+pow2[idx])%mod;
    if(k == 1) break;
    k = (k+1)/2;
    --idx;
  }
  cout << ans;
  return 0;
}

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