Cod sursa(job #2920720)
Utilizator | Data | 25 august 2022 15:43:57 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva educationala | Marime | 0.6 kb |
#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("ciur.in");
ofstream fout("ciur.out");
bool neprim[2000005];
void ciur(int maxval)
{
neprim[0] = 1;
neprim[1] = 1;
for(int i = 2; i * i <= maxval; i++)
{
if(neprim[i] == 0)
{
for(int j = 2; i * j <= maxval; j++)
neprim[i*j] = 1;
}
}
}
int main()
{
int n;
fin >> n;
ciur(n);
int nrprim = 0;
for(int i = 1; i <= n; i++)
{
if(neprim[i] == 0)
nrprim++;
}
fout << nrprim;
return 0;
}