Cod sursa(job #2066144)
Utilizator | miruna mirunaF | Data | 14 noiembrie 2017 18:40:19 |
---|---|---|---|
Problema | Numarare triunghiuri | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.64 kb |
#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;
ifstream in("nrtri.in");
ofstream out("nrtri.out");
const int N=801,L=15;
int n, v[N] , nr ;
int caut_bin ( int S)
{
int pas = 1<<L , r=0;
while (pas != 0)
{
if( r+pas <= n && v[r+pas] <= S )
{
r+=pas;
}
pas/=2;
}
return r;
}
int main()
{
int i , j ;
in>>n;
for(i=1;i<=n;i++)
in>>v[i];
sort(v+1, v+n+1);
for(i=1; i<n; i++)
for(j= i+1 ; j <=n ;j++)
nr += caut_bin(v[i]+v[j]) - j;
out<<nr;
return 0;
}