Submission #1094019

#	Time	Username	Problem	Language	Result	Execution time	Memory
1094019		MrNanama	Rack (eJOI19_rack)	C++17	100 / 100	0 ms	348 KiB

rack

#include <bits/stdc++.h>
#define pb push_back
#define fi first
#define se second

using namespace std;
using ll = long long;
const ll MOD = (1000000007);

template <typename T> ostream& operator<<(ostream& os, const vector<T>& vec){for (auto itr : vec){os << itr << " ";} return os;}

ll n,k;
ll ans;

ll fpow(ll b, ll p){
	if(b == 0){return 0;}
	if(p == 0){return 1;}
	if(p == 1){return b;}

	ll a = fpow(b, p/2)%MOD;
	a = (a*a)%MOD;

	if(p%2){a = (a*b)%MOD;}

	return a%MOD;
}

void solve(){

	cin >> n >> k;
	ans = 0;
	k--;

	for(ll p=0; p<62; p++){
		if((k>>p)&1){
			ans = (ans+ fpow(2,n-p-1))%MOD;
		}
	}

	cout << ans+1 << endl;
}

int main(){

	ios_base::sync_with_stdio(false); cin.tie(NULL);

	solve();
}

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