Submission #703245

#	Time	Username	Problem	Language	Result	Execution time	Memory
703245		rainboy	Rack (eJOI19_rack)	C11	100 / 100	1 ms	288 KiB

rack

#include <stdio.h>

#define MD	1000000007

long long power(long long a, int k) {
	long long p = 1;

	while (k) {
		if (k & 1)
			p = p * a % MD;
		a = a * a % MD;
		k >>= 1;
	}
	return p;
}

int main() {
	int n, ans;
	long long k;

	scanf("%d%lld", &n, &k), k--;
	ans = 1;
	while (k) {
		n--;
		if (k & 1)
			ans = (ans + power(2, n)) % MD;
		k >>= 1;
	}
	printf("%d\n", ans);
	return 0;
}

Compilation message (stderr)

rack.c: In function 'main':
rack.c:21:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   21 |  scanf("%d%lld", &n, &k), k--;
      |  ^~~~~~~~~~~~~~~~~~~~~~~

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