Cod sursa(job #539580)

Utilizator dragosd2000Dumitrache Dragos dragosd2000 Data 23 februarie 2011 08:34:10
Problema Ciurul lui Eratosthenes Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.32 kb
Raporteaza aceasta sursa 
#include<fstream.h>
ifstream fin("ciur.in");
ofstream fout("ciur.out");
unsigned char a[2000001];
long n;
int main()
{
	long i,j, nr=0;
	fin>>n;
	a[0]=1;
	a[1]=1;
	for(i=2;i*i<=n;i++)
		if(a[i]==0)
			for(j=2*i;j<=n;j=j+i)
				a[j]=1;
	for(i=2;i<=n;i++)
		if(a[i]==0)
			nr++;
	fout<<nr;
		
	return 0;
}