Cod sursa(job #876347)
Utilizator | rusu bogdan bogdan1515 | Data | 11 februarie 2013 18:30:46 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.5 kb |
#include<iostream>
#include<fstream>
#include<cmath>
using namespace std;
int ciur( bool *a,long n)
{
int c=0,i,j;
a[1]=false;
for(i=2;i<=n;i++)
a[i]=true;
for( i=2; i<=sqrtl(n); i++)
if(a[i]==true)
for( j=i*i;j<=n;j+=i)
if (a[j]==true)
{
a[j]=false;
c++;
}
return n-1-c;
}
int main()
{
ifstream f("ciur.in");
ofstream g("ciur.out");
long n;
f>>n;
bool *a;
a=(bool*)malloc(n*sizeof(bool));
int c=ciur(a,n);
g<<c;
return 0;
}