Cod sursa(job #477033)

Utilizator barneystinsonBarney barneystinson Data 13 august 2010 02:04:01
Problema Ciurul lui Eratosthenes Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.34 kb
Raporteaza aceasta sursa 
#include <cstdio>

FILE*f=fopen("ciur.in","r");
FILE*g=fopen("ciur.out","w");

char prim[2000001];

int main(){
	
	int x,nr=0,i,j;
	
	fscanf(f,"%d",&x);
	
	for( i=2;i <= x;i++){
		if(!prim[i]){
			nr++;
			for( j=i+i;j<=x;j+=i){
				prim[j]=1;
			}
		}
		
	}
	
	fprintf(g,"%d",nr);
	
	fclose(f);
	fclose(g);
	return 0;
}