Submission #1080089

#	Time	Username	Problem	Language	Result	Execution time	Memory
1080089		mariza	Rack (eJOI19_rack)	C++14	40 / 100	1 ms	348 KiB

rack

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
const ll MOD=1e9+7;

ll mpow(ll b, ll e, ll m){
    if(e==0) return 1;
    else if(e%2==0) return mpow((b*b)%m,e/2,m)%m;
    else return (b*mpow(b*b,e/2,m))%m;
}

int main(){
    ll n, k;
    cin>>n>>k; k--;

    ll ans=0;
    for(ll i=0; i<60; i++){
        if(k&(1ll<<i)) ans+=mpow(2,n-i-1,MOD);
        ans%=MOD;
        // cout<<i<<" "<<ans<<endl;
    }
    ans++;
    ans%=MOD;
    cout<<ans<<endl;
}

• Subtask 1: 20 / 20
• Subtask 2: 20 / 20
• Subtask 3: 0 / 60