Cod sursa(job #561677)

Utilizator SadmannCornigeanu Calin Sadmann Data 21 martie 2011 08:35:54
Problema Ciurul lui Eratosthenes Scor 30
Compilator cpp Status done
Runda Arhiva educationala Marime 0.35 kb
Raporteaza aceasta sursa 
#include<stdio.h>
#include<vector>
using namespace std;
FILE *in=fopen("ciur.in","rt");
FILE *out=fopen("ciur.out","wt");

int i,j,n,cont;
int main()
{
	fscanf(in,"%d",&n);
    vector<int> prim(n+1);
	cont=1;
	for(i=3;i<=n;i+=2)
	{
		if(!prim[i])
		{
			for(j=i<<1;j<=n;j+=i)
				prim[j]=true;
			cont++;
		}
	}
	fprintf(out,"%d",cont);
}