Submission #639123

#	Time	Username	Problem	Language	Result	Execution time	Memory
639123		irmuun	Rack (eJOI19_rack)	C++17	100 / 100	3 ms	340 KiB

rack

#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define ll long long
#define ff first
#define ss second
#define pi pair<ll,ll>
#define PI 3.1415926535897932384626433

const ll mod=1000000007,mod1=998244353,INF=1e18,MAX=1e9;

int main(){
    //freopen("input.txt","r",stdin);
    //freopen("output.txt","w",stdout);
    cin.tie(0),cout.tie(0),ios_base::sync_with_stdio(false);
    ll n,k;
    cin>>n>>k;
    auto fastPow=[&](ll a,ll b) {
        ll res=1;
        while(b>0){
            if(b%2==1){
                res*=a;
                res%=mod;
            }
            b/=2;
            a=a*a%mod;
        }
        return res;
    };
    ll v=1;
    ll ans=1;
    while(v!=n+1){
        if(k%2==0){
            ans+=fastPow(2,n-v);
            ans%=mod;
        }
        k=k/2+k%2;
        v++;
    }
    cout<<ans;
}

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