Submission #244584

#	Time	Username	Problem	Language	Result	Execution time	Memory
244584		Matteo_Verz	Rack (eJOI19_rack)	C++11	100 / 100	5 ms	388 KiB

rack

/*
                `-/oo+/-   ``
              .oyhhhhhhyo.`od
             +hhhhyyoooos. h/
            +hhyso++oosy- /s
           .yoooossyyo:``-y`
            ..----.` ``.-/+:.`
                   `````..-::/.
                  `..```.-::///`
                 `-.....--::::/:
                `.......--::////:
               `...`....---:::://:
             `......``..--:::::///:`
            `---.......--:::::////+/`
            ----------::::::/::///++:
            ----:---:::::///////////:`
            .----::::::////////////:-`
            `----::::::::::/::::::::-
             `.-----:::::::::::::::-
               ...----:::::::::/:-`
                 `.---::/+osss+:`
                   ``.:://///-.
*/
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <cmath>

using namespace std;
using i64 = long long;

const int INF = 2e9;
const int MOD = 1e9 + 7;

i64 lgput(i64 b, i64 e) {
    i64 r(1);

    while(e) {
        if(e & 1) r = (r * b) % MOD;
        b = (b * b) % MOD;
        e >>= 1;
    }

    return r;
}

int main() {
    #ifdef BLAT
    freopen("input.in", "r", stdin);
    freopen("output.out", "w", stdout);
    #endif // BLAT
    ios_base::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);

    i64 n, k, ans(0);
    cin >> n >> k;
    k--;

    for(i64 i = 0; (1LL << i) <= k; i++) {
        if(k & (1LL << i)) {
            ans = ans + lgput(2, n - i - 1);
            ans %= MOD;
        }
    }

    ans++;
    ans %= MOD;
    cout << ans << '\n';
    return 0;
}

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