Cod sursa(job #1331267)
Utilizator | Constantin-Buliga Stefan fanache99 | Data | 31 ianuarie 2015 14:53:38 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.51 kb |
#include<stdio.h>
using namespace std;
char ciur[2000001];
void ciurr(int nrmax){
int prim=2,m ;
while(prim*prim<=nrmax){
for(m=2;m<=nrmax/prim;m++)
ciur[m*prim]=1;
prim++;
while(ciur[prim]==1)
prim++;
}
}
int main(){
freopen("ciur.in","r",stdin);
freopen("ciur.out","w",stdout);
int n,i,nr=0;
scanf("%d",&n);
ciurr(n);
for(i=2;i<=n;i++)
if(ciur[i]==0)
nr++;
printf("%d",nr);
return 0;
}