Submission #1097485

#	Time	Username	Problem	Language	Result	Execution time	Memory
1097485		vjudge1	Rack (eJOI19_rack)	C++17	40 / 100	1 ms	600 KiB

rack

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

using ll = long long int;

const int MOD = 1e9 + 7;

int log2_floor(unsigned long long x) {
    return x ? __builtin_clzll(1) - __builtin_clzll(x) : -1;
}

int pow(int b, int p) {
    if (!p) return 1;
    int p2 = pow(b, p >> 1);
    return (1LL * p2 * p2 * (p & 1 ? b : 1)) % MOD;
}

int test(int n, ll k) {
    k--;
    ll result = 1;

    while (k) {
        ll mask = k & (-k);
        result = (result + pow(2, n - log2_floor(mask) - 1)) % MOD;
        k ^= mask;
    }

    return result % MOD;
}

int main() {
    int n, k;
    scanf("%d %d", &n, &k);
    printf("%d\n", test(n, k));
    return 0;
}

Compilation message (stderr)

rack.cpp: In function 'int main()':
rack.cpp:33:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   33 |     scanf("%d %d", &n, &k);
      |     ~~~~~^~~~~~~~~~~~~~~~~

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