Submission #893840

#	Time	Username	Problem	Language	Result	Execution time	Memory
893840		Essa2006	Rack (eJOI19_rack)	C++14	100 / 100	12 ms	4188 KiB

rack

#include<bits/stdc++.h>
using namespace std;
#define ll long long 
#define endl '\n'
#define FF first
#define SS second
#define all(a) a.begin(), a.end()
#define mod (ll)(1000000007)

int add(ll a, ll b) {
    ll res = a + b;
    return res % mod;
}

int mul(ll a, ll b) {
    a %= mod, b %= mod;
    ll res = a * b;
    return res % mod;
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    
    ll n, k;
    cin >> n >> k;
    
    vector<int> Pwr_of_two(n+1);
    Pwr_of_two.front() = 1;
    for (int i = 1; i <= n; i++) {
        Pwr_of_two[i] = mul(Pwr_of_two[i - 1], 2);
    }
    
    ll ans = 1;
    for (int i = n - 1; i >= 0; i--) {
        if (k % 2 == 0) {
            ans = add(ans, Pwr_of_two[i]);
        }
        k = (k + 1) / 2;
    }
    cout << ans;
}

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