Submission #1245285

#	Time	Username	Problem	Language	Result	Execution time	Memory
1245285		boyan2010	Rack (eJOI19_rack)	C++20	100 / 100	97 ms	408 KiB

rack

#include<bits/stdc++.h>
using namespace std;
long long n,k;
const long long mod=1e9+7;
long long f(long long k)
{
    if(k==0)
    {
        return 0;
    }
    long long pow=0,prod=1;
    while(prod<=k)
    {
        prod*=2;
        pow++;
    }
    prod/=2;
    pow--;
    long long one=1;
    for(int i=1;i<n-pow;i++)
    {
        one*=2;
        one%=mod;
    }
    return (f(k-prod)+one)%mod;
}
int main()
{
    cin>>n>>k;
    if(k==1)
    {
        cout<<1;
        return 0;
    }
    k--;
    cout<<(f(k)+1)%mod;
    return 0;
}

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