Cod sursa(job #2100184)
Utilizator | Data | 5 ianuarie 2018 12:48:52 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.39 kb |
#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("ciur.in");
ofstream fout("ciur.out");
long n,ciur[200000001],j,d,i,num;
int main()
{
fin>>n;
ciur[0]=ciur[1]=1;
for(d=2;d*d<=n;d++)
{
if (!ciur[d])
for (j=2;j*d<=n;j++) ciur[j*d]=1;
}
for(i=2;i<n;i++)
if(ciur[i]==0) num++;
fout<<num;
return 0;
}