Submission #581060

#	Time	Username	Problem	Language	Result	Execution time	Memory
581060		vanea	Rack (eJOI19_rack)	C++14	100 / 100	3 ms	296 KiB

rack

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

using ll = long long;
const int mod = 1e9+7;

ll power(int x, int y)
{
    ll temp;
    if(y == 0)
        return 1;
    temp = power(x, y / 2);
    if (y % 2 == 0)
        return (temp * temp) % mod;
    else {
        if(y > 0)
            return (x * temp * temp)%mod;
        else
            return ((temp * temp) / x) % mod;
    }
}

int main()
{
    ll n, k;
    cin >> n >> k;
    if(k == 1) {
        cout << 1;
        return 0;
    }
    ll ans = 1;
    for(int i = n-1; i >= 0; i--) {
        if(k % 2 == 1) {
            k = k / 2 + 1;
        }
        else {
            k /= 2;
            ans += power(2, i);
            ans %= mod;
        }
    }
    cout << ans;
    return 0;
}

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