Cod sursa(job #2181354)
Utilizator | Piscu Stefan Constantin Stefan_Piscu | Data | 21 martie 2018 17:08:03 |
---|---|---|---|
Problema | Numarare triunghiuri | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.67 kb |
#include <fstream>
#include <algorithm>
using namespace std;
int v[10001];
ifstream f("nrtri.in");
ofstream g("nrtri.out");
int cautbin(int x,int n)
{
int p=1,u=n,poz=-1,m;
while(p<=u)
{
m=(p+u)/2;
if(x>=v[m])
{
poz=m;
p=m+1;
}
else
u=m-1;
}
return poz;
}
int main()
{
int n, poz=0, nr=0;
f>>n;
for(int i=1;i<=n;++i) f>>v[i];
sort(v+1 ,v+n+1);
for(int i=1;i<=n-2;i++)
for(int j=i+1;j<=n-1;j++)
{
poz=cautbin(v[i]+v[j],n);
if(poz!=-1) nr=nr+poz-j;
}
g<<nr<<"\n";
return 0;
}