Cod sursa(job #392678)
Utilizator | Data | 8 februarie 2010 00:16:43 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.45 kb |
#include<iostream>
#include<fstream>
#include<stdio.h>
#include<vector>
using namespace std;
char v[2000005];
int main()
{int k,n;
int j,i;
ifstream fin("ciur.in");
fin>>n;
v[0]=v[1]=1;
k=0;
for (i = 2; i <= n; ++i)
v[i] = 1;
for(i=2;i<=n;i++)
{if(v[i]==1)
k++;
for(j=i+i;j<=n;j+=i)
{v[j]=0;
}
}
fin.close();
freopen("ciur.out","w",stdout);
printf("%d \n",k);
return 0;
}