Submission #217942

#	Time	Username	Problem	Language	Result	Execution time	Memory
217942		Sho10	Rack (eJOI19_rack)	C++14	100 / 100	5 ms	384 KiB

rack

/*
ID: Sho10
LANG: C++
*/
#include <bits/stdc++.h> //Andrei Alexandru a.k.a Sho10
#define ll long long int
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#define all(a) (a).begin(), (a).end()
#define sz size
#define f first
#define s second
#define pb push_back
#define er erase
#define in insert
#define mp make_pair
#define pi pair
#define rc(s) return cout<<s,0
#define endl '\n'
#define mod 1000000007
#define PI 3.14159265359
#define CODE_START  ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
using namespace std;
ll n,k;
ll pw(ll a,ll b){
    if(b==0) return 1;
    ll n=pw(a,b/2);
    if(b%2==1){
            return (((n*n)%mod)*a)%mod;
    }else return (n*n)%mod;
}
int32_t main(){
CODE_START;
cin>>n>>k;
ll ans=1,s1=1;
while(k!=1){
    if(k%2==0){
        ans=ans+pw(2LL,n-s1);
        ans=ans%mod;
        s1++;
        ll val=k/2;
        k=k-val;
    }else {
    s1++;
    ll val=k/2;
    k=k-val;
    }
}
cout<<ans<<endl;
}

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