Submission #844641

#	Time	Username	Problem	Language	Result	Execution time	Memory
844641		EntityPlantt	Rack (eJOI19_rack)	C++14	100 / 100	2 ms	348 KiB

rack

#include <cstdio>
#define int long long
const int mod = 1000000007;
int n, k, i, r = 1;
int pow2(int x) {
    if (!x) return 1;
    if (x & 1) return 2 * pow2(x / 2) % mod * pow2(x / 2) % mod;
    return pow2(x / 2) * pow2(x / 2) % mod;
}
signed main() {
    scanf("%lld%lld", &n, &k);
    for (i = n - 1; i >= 0; i--) {
        if (k & 1) k++;
        else r = (r + pow2(i)) % mod;
        k = (k + 1) / 2;
    }
    printf("%lld", r);
    return 0;
}

Compilation message (stderr)

rack.cpp: In function 'int main()':
rack.cpp:11:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   11 |     scanf("%lld%lld", &n, &k);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~

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