Cod sursa(job #365320)
Utilizator | Data | 18 noiembrie 2009 13:50:55 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 20 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.48 kb |
#include <fstream>
using namespace std;
ifstream in("ciur.in");
ofstream out("ciur.out");
unsigned int N,x,nr,b;
int main()
{
in>>N;
if(N>=3)
{
x=3;
nr++;
while(x<=N)
{
b=1;
if(x%2!=0)
{
if(x%5!=0 || x==5)
{
unsigned int d=2;
b=0;
while(d<=x/2)
{
if(x%d==0)b=1;
d++;
}
}
}
if(b==0)nr++;
x=x+2;
}
out<<nr;
}
else out<<1;
in.close();
out.close();
return 0;
}