Submission #767340

#	Time	Username	Problem	Language	Result	Execution time	Memory
767340		ihceker	Rack (eJOI19_rack)	C++14	100 / 100	1 ms	300 KiB

rack

#include<bits/stdc++.h>
#define int long long
#define MOD 1000000007
#define all(x) x.begin(),x.end()
#define ff first
#define ss second
#define pb push_back
#define fast ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);

using namespace std;

int fp(int a,int b){
	if(b==0)return 1;
	int t=fp(a,b/2);
	t=(t*t)%MOD;
	if(b%2)return (t*a)%MOD;
	return t;
}

int32_t main(){
	int n,k;
	cin>>n>>k;
	int ans=1,x=fp(2,n-1);
	k--;
	for(int i=1;i<=1e18;i*=2){
		if(k&i){
			ans=(ans+x)%MOD;
		}
		x=(x*fp(2,MOD-2))%MOD;
	}
	cout<<ans<<endl;
}

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