Submission #19001

#	Time	Username	Problem	Language	Result	Execution time	Memory
19001		kriii	순열 (kriii4_T)	C++14	100 / 100	46 ms	8896 KiB

T

#include <stdio.h>

const long long mod = 1000000007;

long long inv[1000001];

int main()
{
	long long n,k,f=1,a=0; scanf ("%lld %lld",&n,&k);
	inv[1] = 1;
	for (long long l=1;l<=n;l++){
		inv[l+1] = (mod - mod / (l + 1)) * inv[mod % (l + 1)] % mod;
		if (l > k) a = (a + inv[l + 1] * (n - l + 1)) % mod;
		f = f * (l + 1) % mod;
	}
	printf ("%lld\n",a*f%mod);

	return 0;
}

• Subtask 1: 8 / 8
• Subtask 2: 92 / 92