Cod sursa(job #2492479)
Utilizator | Data | 14 noiembrie 2019 20:05:14 | |
---|---|---|---|
Problema | Numarare triunghiuri | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva de probleme | Marime | 0.86 kb |
#include <fstream>
#include <algorithm>
using namespace std;
ifstream fin("nrtri.in");
ofstream fout("nrtri.out");
int n,i,j,u,a[1001],poz,p,nr,x,mj;
int main()
{
fin>>n;
for(i=1; i<=n; i++)fin>>a[i];
sort(a+1,a+n+1);
nr=0;
for(i=1; i<=n-2; i++)
for(j=i+1; j<=n-1; j++)
{
x=a[i]+a[j];
p=j+1;
u=n;
while(p<u)
{
mj=(p+u)/2;
if(x>=a[mj])
{
poz=mj;
p=mj+1;
}
else u=mj;
}
mj= (p + u) / 2;
if (a[mj] <x)
++ mj;
poz=mj;
if(poz==n&&a[n]<=x)poz++;
//fout<<a[i]<<" "<<a[j]<<" "<<poz<<endl;
if(poz>j+1)nr=nr+poz-j-1;
}
fout<<nr;
return 0;
}