| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 2415 | hana5505 | 지우개 (GA4_eraser) | C++98 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include<stdio.h>
int mod=1000000007;
long long ar[100001];
int aa[100001];
long long sum1[100001];
long long sum2[100001];
int main()
{
long long s=0;
int n,i,size=0;
scanf("%d",&n);
for(i=1;i<=n;i++){
scanf("%lld",&ar[i]);
aa[(int)ar[i]]++;
}
for(i=1;i<=100000;i++){
if(aa[i])
ar[++size]=i;
}
for(i=1;i<=size;i++){
sum1[i]=( sum1[i-1]+(ar[i]*aa[ar[i]])%mod )%mod;
sum2[i]=( sum2[i-1]+(( (ar[i]*aa[ar[i]])%mod )*( (ar[i]*aa[ar[i]])%mod )%mod);
}
for(i=1;i<=size-2;i++){
s+=aa[(int)ar[i]]*ar[i]*(((((sum1[size]-sum1[i])%mod)*((sum1[size]-sum1[i])%mod)-(sum2[size]-sum2[i]))/2)%mod);
s=s%mod;
}
printf("%lld",s);
}