Cod sursa(job #1388357)
Utilizator | Data | 15 martie 2015 13:39:12 | |
---|---|---|---|
Problema | Medie | Scor | 100 |
Compilator | c | Status | done |
Runda | Arhiva de probleme | Marime | 0.57 kb |
#include<stdio.h>
#define N 7001
int cate[N];
int main()
{
FILE *fin,*fout;
fin=fopen("medie.in","r");
fout=fopen("medie.out","w");
int n;
fscanf(fin,"%d",&n);
int i;
for(i=0;i<n;i++)
{
int nr;
fscanf(fin,"%d",&nr);
cate[nr]++;
}
long long sol=0;
for(i=0;i<N;i++)
{
sol+=((long long)(cate[i]-1)*cate[i]*(cate[i]-2))/2;
int j;
for(j=i+2;j<N;j+=2)
sol+=(long long)cate[j]*cate[i]*cate[(i+j)/2];
}
fprintf(fout,"%lld\n",sol);
return 0;
}