Submission #9325

#	TimeUTC-0	Username	Problem	Language	Result	Execution time	Memory
9325	2014-09-28 05:36:18	myungwoo	Uniting (kriii2_U)	C++14	4 / 4	12 ms	1088 KiB

U

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#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;
}
 
 
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• Subtask 1: 4 / 4