Submission #9325

#	Time	Username	Problem	Language	Result	Execution time	Memory
9325		myungwoo	Uniting (kriii2_U)	C++14	4 / 4	12 ms	1088 KiB

U

#include<stdio.h>
#define mod 1000000007

typedef long long lld;
lld n, s, sum, sqsum, fac=1;

int main(){
	lld i;
	scanf("%lld", &n);
	for(i=0; i<n; i++){
		scanf("%lld", &s);
		sum+=s, sqsum+=s*s;
	}
	for(i=n; i>=2; i--){
		fac=(fac*i)%mod;
		fac=(fac*(i-1))%mod;
	}
	printf("%lld\n%lld", (sum*sum-sqsum)/2, fac);
	return 0;
}

• Subtask 1: 4 / 4