Submission #675720

#	Time	Username	Problem	Language	Result	Execution time	Memory
675720		Alma	Rack (eJOI19_rack)	C++17	0 / 100	1096 ms	212 KiB

rack

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

using ll = long long;
ll MOD = 1e9+7;

ll calcMODpow(int b, int p) {
    if (p == 0) return 1;
    ll x = calcMODpow(b, p/2);
    if (p % 2 == 1) {
        return (((x*x) % MOD)*b) % MOD;
    } else {
        return (x*x) % MOD;
    }
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(NULL);

    ll n, k;
    cin >> n >> k;
    ll pos = 1, add = n;
    bool inv = false;

    int i = 0;
    while (i < n) {
        if ((1 << i) > k) {
            break;
        }
        add--;
        if (inv == false) {
            if ((k & (1 << i))) {
                inv = true;
            } else {
                pos += calcMODpow(2, add);
                pos %= MOD;
            }
        } else {
            if ((k & (1 << i))) {
                pos += calcMODpow(2, add);
                pos %= MOD;
            } else {
                inv = true;
            }
        }
        i++;
    }
    while (i < n) {
        add--;
        if (inv) {
            pos += calcMODpow(2, add);
            pos %= MOD;
        }
    }

    cout << pos << '\n';

    return 0;
}

• Subtask 1: 0 / 20
• Subtask 2: 0 / 20
• Subtask 3: 0 / 60