Cod sursa(job #2205916)

Utilizator alex273Groza Alexandru alex273 Data 20 mai 2018 16:29:40
Problema Ciurul lui Eratosthenes Scor 30
Compilator cpp Status done
Runda Arhiva educationala Marime 0.32 kb
Raporteaza aceasta sursa 
#include <iostream>
#include <fstream>

using namespace std;

ifstream fin("ciur.in");
ofstream fout("ciur.out");

char b[2000001];

int main(){
	int n, k = 1;
	fin>>n;
	for(int i = 1;2*i + 1 <= n; ++i)
	if(!b[i])
	{		
		++k;
		for(int j = (2*i*i) + (2*i);2*j + 1 <= n; j += 2*i + 1)
			b[j] = 1;
	}	
	fout<<k;
	return 0;
}