Submission #884737

#	Time	Username	Problem	Language	Result	Execution time	Memory
884737		Perl32	Rack (eJOI19_rack)	C++14	100 / 100	2 ms	348 KiB

rack

/**
 *    author:  Perl32
 *    created: 18.11.2023 09:12:21
**/

#ifdef LOCAL
#  define _GLIBCXX_DEBUG
#endif
#include <bits/stdc++.h>
#define ff first
#define ss second
#define szof(x) (int) x.size()
#define all(x) x.begin(), x.end()
#ifndef LOCAL
#  define cerr if (0) cerr
#endif

using namespace std;
using ll = long long;
using ld = long double;
using pll = pair<ll, ll>;
using pii = pair<int, int>;
using ull = unsigned long long;

template<typename T> bool ckmin(T &a, const T &b) { return b < a ? a = b, 1 : 0; }
template<typename T> bool ckmax(T &a, const T &b) { return a < b ? a = b, 1 : 0; }

const int INF = (int) 1e9 + 1e3;
const ll INFL = (ll) 1e18 + 1e9;
#ifdef LOCAL
    mt19937 tw(9450189);
#else
    mt19937 tw(chrono::high_resolution_clock::now().time_since_epoch().count());
#endif
uniform_int_distribution<ll> ll_distr;
ll rnd(ll a, ll b) { return ll_distr(tw) % (b - a + 1) + a; }

const ll MOD = (ll) 1e9 + 7;

ll binpow(ll a, ll n) {
    ll ret = 1;
    while (n) {
        if (n & 1) {
            ret = (ret * a) % MOD;
            --n;
        }
        a = (a * a) % MOD;
        n >>= 1;
    }
    return ret;
}

signed main() {
#ifdef LOCAL
    freopen("inp.txt", "r", stdin);
    freopen("out.txt", "w", stdout);
    freopen("err.txt", "w", stderr);
    auto start_time = clock();
    cerr << setprecision(3) << fixed;
#endif
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    ll n, k;
    cin >> n >> k;
    ll ans = 1;
    for (ll i = n - 1; i >= 0; --i) {
        if (k & 1) {
            k++;
        } else {
            ans = (ans + binpow(2, i)) % MOD;
        }
        k = (k + 1) / 2;
    }
    cout << ans;

#ifdef LOCAL
    auto end_time = clock();
    cerr << "Execution time: " << (end_time - start_time) * (ll) 1e3 / CLOCKS_PER_SEC << " ms\n";
#endif
}

/*

 */

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