Cod sursa(job #766393)
Utilizator | duta danut ametistum | Data | 11 iulie 2012 10:33:42 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.42 kb |
#include <iostream>
#include<fstream>
#include<bitset>
using namespace std;
ifstream f("ciur.in");
ofstream g("ciur.out");
int n,i,j,sol;
bitset<2000010> p;
int main()
{
f>>n;
for(i=2;i*i<=n;i++)
{
if(!p[i])
{
sol++;
for(j=i*i;j<=n;j+=i)
p[j]=1;
}
}
for(;i<=n;i++)
if(!p[i])
sol++;
g<<sol;
return 0;
}