Cod sursa(job #936686)
Utilizator | Data | 8 aprilie 2013 12:25:52 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.37 kb |
#include <iostream>
#include <fstream>
#include <ctime>
using namespace std;
ifstream f("ciur.in");
ofstream g("ciur.out");
int n,sol=1;
bool p[50000005];
void Ciur()
{ long long i,j;
for(i=3;i<=n;i+=2)
{ if (!p[i])
{ sol++;
for(j=i*i;j<=n;j+=i+i) p[j]=1;
}
}
}
int main()
{ f>>n;
Ciur();
g<<sol;
return 0;
}