Submission #19001

#	TimeUTC-0	Username	Problem	Language	Result	Execution time	Memory
19001	2016-02-17 02:53:18	kriii	순열 (kriii4_T)	C++14	100 / 100	46 ms	8896 KiB

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#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;
}
 
 
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• Subtask 1: 8 / 8
• Subtask 2: 92 / 92