Submission #463618

#	Time	Username	Problem	Language	Result	Execution time	Memory
463618		Elias	Rack (eJOI19_rack)	C++17	100 / 100	13 ms	7884 KiB

rack

#include <bits/stdc++.h>

using namespace std;

#define int long long

#define modder 1000000007LL

vector<int> power2Mod;

int solve(int n, int k)
{
	if (n == 0)
		return 1;
	if (k % 2LL) // k is odd -> left subtree
		return solve(n - 1LL, (k + 1LL) / 2LL);
	else
		return (solve(n - 1, k / 2) + power2Mod[n - 1]) % modder;
}

signed main()
{
	cin.tie(0);
	ios_base::sync_with_stdio(false);
	int n, k;
	cin >> n >> k;

	power2Mod = vector<int>(n, 1);

	for (int i = 1; i < n; i++)
	{
		power2Mod[i] = (power2Mod[i - 1] * 2) % modder;
	}

	cout << solve(n, k);
}

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