Submission #58895

#	Time	Username	Problem	Language	Result	Execution time	Memory
58895		TadijaSebez	Asceticism (JOI18_asceticism)	C++11	0 / 100	6 ms	1912 KiB

asceticism

#include <stdio.h>
#define ll long long
const int N=200050;
const int mod=1000000007;
int F[N],I[N];
int pow(int x, int k){ int ret=1;for(;k;k>>=1,x=(ll)x*x%mod) if(k&1) ret=(ll)ret*x%mod;return ret;}
int get(int n, int k){ return (ll)F[n]*I[k]%mod*I[n-k]%mod;}
int calc(int n, int k)
{
	if(k>n) return 0;
	int ret=0;
	for(int i=0;i<=k;i++)
	{
		int add=(ll)get(i,n+1)*pow(k+1-i,n)%mod;
		if(i&1) ret=(ret-add+mod)%mod;
		else ret=(ret+add)%mod;
	}
	return ret;
}
int main()
{
	int n,k,x,i,sum=0;
	F[0]=1;for(i=1;i<N;i++) F[i]=(ll)F[i-1]*i%mod;
	I[N-1]=pow(F[N-1],mod-2);for(i=N-2;i>=0;i--) I[i]=(ll)I[i+1]*(i+1)%mod;
	scanf("%i %i",&n,&k);
	printf("%i\n",calc(n,k-1));
	return 0;
}

Compilation message (stderr)

asceticism.cpp: In function 'int main()':
asceticism.cpp:22:10: warning: unused variable 'x' [-Wunused-variable]
  int n,k,x,i,sum=0;
          ^
asceticism.cpp:22:14: warning: unused variable 'sum' [-Wunused-variable]
  int n,k,x,i,sum=0;
              ^~~
asceticism.cpp:25:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%i %i",&n,&k);
  ~~~~~^~~~~~~~~~~~~~~

• Subtask 1: 0 / 4
• Subtask 2: 0 / 20
• Subtask 3: 0 / 25
• Subtask 4: 0 / 51