Cod sursa(job #1423506)

Utilizator TeodorescuStefanEduardTeodorescu Stefan Eduard TeodorescuStefanEduard Data 21 aprilie 2015 22:00:42
Problema Ciurul lui Eratosthenes Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 0.51 kb
#include <iostream>
#include <fstream>
#include <math.h>

using namespace std;

fstream in("ciur.in",ios::in);
fstream out("ciur.out",ios::out);

int prim(int);

int main()
{
    int n,ciur[2000001]={},i,j,k=1;

    in>>n;

    for(i=2;i*i<=n;i++)
        for(j=i*i;j<=n;j=j+i)
        {
            if(ciur[j]==0)
                k++;
            ciur[j]=1;
        }
    out<<n-k;




    return 0;
}

int prim(int nr)
{
    int i,j,p=1;

    for(i=2;i<=sqrt(nr);i++)
        if(nr%i==0)
            p=0;
    return p;



}