Cod sursa(job #1710964)
Utilizator | Turcas David Emil DologX | Data | 30 mai 2016 08:31:38 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.45 kb |
#include <iostream>
#include <fstream>
#include <math.h>
using namespace std;
bool p[2000000];
int n;
void ciur()
{
for(int i=2;i<=sqrt(n);i++)
{
if(p[i]==0) for(int j=i*i;j<=n;j=j+i) p[j]=1;
}
}
int main()
{
int nr = 0;
ifstream f("ciur.in");
ofstream g("ciur.out");
f>>n;
ciur();
for(int i = 2; i <= n; ++i)
if(p[i]==0) // sau if(!p[i])
++nr;
g << nr;
}