Cod sursa(job #773294)
Utilizator | Andreea Gabriela gabriela95 | Data | 1 august 2012 13:21:42 |
---|---|---|---|
Problema | Numarare triunghiuri | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.53 kb |
#include <fstream>
#include <algorithm>
using namespace std;
ifstream f("nrtri.in");
ofstream g("nrtri.out");
int n,i,a[800],j,nr=0,p,u,m,x;
int main()
{
f>>n;
for(i=0;i<n;i++)
f>>a[i];
sort(a,a+n);
for(i=0;i<n-2;i++)
for(j=i+1;j<n-1;j++)
{
x=a[i]+a[j];
p=j+1;
u=n-1;
m=(p+u)/2;
while(p!=u)
{
if(a[m]>x)
u=m-1;
if(a[m]<x)
p=m+1;
if(a[m]==x)
break;
}
m=(p+u)/2;
if(a[m]==x)
nr+=(m-j);
if((a[m]>=x)&&(a[m-1]<=x))
nr+=(m-j)-1;
}
g<<nr;
return 0;
}